feat: delimit between images in validate output

[willmurphyscode]

Otherwise, it's easy for an operator to investigate the wrong image when investigating a quality gate failure.

Example of new output:

   Results used for image docker.io/anchore/test_images@sha256:c8d664b0e728d52f57eeb98ed1899c16d3b265f02ddfb41303d7a16c31e0b0f1:
    ├── 86723334-feee-4a64-8d9f-5878bfb3ee34 : grype[candidate]@path:../../+import-db=db.tar.gz (candidate)  against docker.io/anchore/test_images@sha256:c8d66
4b0e728d52f57eeb98ed1899c16d3b265f02ddfb41303d7a16c31e0b0f1
    └── 4b769e08-5b30-413f-a2b0-5226e03f3dd1 : grype[reference]@v0.86.1 (reference)  against docker.io/anchore/test_images@sha256:c8d664b0e728d52f57eeb98ed1899
c16d3b265f02ddfb41303d7a16c31e0b0f1
Deltas for docker.io/anchore/test_images@sha256:c8d664b0e728d52f57eeb98ed1899c16d3b265f02ddfb41303d7a16c31e0b0f1:
Match differences between tooling (with labels):
   TOOL PARTITION                                         PACKAGE                                             VULNERABILITY   LABEL      COMMENTARY
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  jcl-over-slf4j@0:1.7.25-4.module+el8+5161+5cac467c  CVE-2018-14040  (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  jcl-over-slf4j@0:1.7.25-4.module+el8+5161+5cac467c  CVE-2019-16943  (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  jcl-over-slf4j@0:1.7.25-4.module+el8+5161+5cac467c  CVE-2020-1695   (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  jcl-over-slf4j@0:1.7.25-4.module+el8+5161+5cac467c  CVE-2020-36518  (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  slf4j@0:1.7.25-4.module+el8+5161+5cac467c           CVE-2018-14040  (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  slf4j@0:1.7.25-4.module+el8+5161+5cac467c           CVE-2019-16943  (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  slf4j@0:1.7.25-4.module+el8+5161+5cac467c           CVE-2020-1695   (unknown)
   grype[candidate]@path:../../+import-db=db.tar.gz ONLY  slf4j@0:1.7.25-4.module+el8+5161+5cac467c           CVE-2020-36518  (unknown)

--------------------------------------------------------------------------------
   Results used for image docker.io/anchore/test_images@sha256:524ff8a75f21fd886ec7ed82387766df386671e8b77e898d05786118d5b7880b:
    ├── c14cbb69-43e2-479b-a509-1273ec83b38c : grype[candidate]@path:../../+import-db=db.tar.gz (candidate)  against docker.io/anchore/test_images@sha256:524ff
8a75f21fd886ec7ed82387766df386671e8b77e898d05786118d5b7880b
    └── 1a02b242-db41-48dc-9c18-82f02054f1af : grype[reference]@v0.86.1 (reference)  against docker.io/anchore/test_images@sha256:524ff8a75f21fd886ec7ed8238776
6df386671e8b77e898d05786118d5b7880b
Deltas for docker.io/anchore/test_images@sha256:524ff8a75f21fd886ec7ed82387766df386671e8b77e898d05786118d5b7880b:
Match differences between tooling (with labels):
   TOOL PARTITION                 PACKAGE                                             VULNERABILITY   LABEL          COMMENTARY
   grype[reference]@v0.86.1 ONLY  php-cli@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-cli@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-cli@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-common@7.4.30-1.module_el8.7.0+1190+d11b935a    CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-common@7.4.30-1.module_el8.7.0+1190+d11b935a    CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-common@7.4.30-1.module_el8.7.0+1190+d11b935a    CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-fpm@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-fpm@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-fpm@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-json@7.4.30-1.module_el8.7.0+1190+d11b935a      CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-json@7.4.30-1.module_el8.7.0+1190+d11b935a      CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-json@7.4.30-1.module_el8.7.0+1190+d11b935a      CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-mbstring@7.4.30-1.module_el8.7.0+1190+d11b935a  CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-mbstring@7.4.30-1.module_el8.7.0+1190+d11b935a  CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-mbstring@7.4.30-1.module_el8.7.0+1190+d11b935a  CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-opcache@7.4.30-1.module_el8.7.0+1190+d11b935a   CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-opcache@7.4.30-1.module_el8.7.0+1190+d11b935a   CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-opcache@7.4.30-1.module_el8.7.0+1190+d11b935a   CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-pdo@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-pdo@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-pdo@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php-xml@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-xml@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php-xml@7.4.30-1.module_el8.7.0+1190+d11b935a       CVE-2021-32610  TruePositive   (this is a new FN 😱)
   grype[reference]@v0.86.1 ONLY  php@7.4.30-1.module_el8.7.0+1190+d11b935a           CVE-2021-21707  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php@7.4.30-1.module_el8.7.0+1190+d11b935a           CVE-2021-21708  FalsePositive  (got rid of a former FP 🙌)
   grype[reference]@v0.86.1 ONLY  php@7.4.30-1.module_el8.7.0+1190+d11b935a           CVE-2021-32610  TruePositive   (this is a new FN 😱)

--------------------------------------------------------------------------------
   Results used for image docker.io/anchore/test_images@sha256:fc6f7a37d7e320f6ff3643d4ec9a208adb1462cd16027f045b56563e12bb0461:
    ├── fba9c2d8-dba1-46cb-ac6f-e9ff4264d93e : grype[candidate]@path:../../+import-db=db.tar.gz (candidate)  against docker.io/anchore/test_images@sha256:fc6f7
a37d7e320f6ff3643d4ec9a208adb1462cd16027f045b56563e12bb0461
    └── 864b4b43-5137-4192-a2ef-eb6a266b14c7 : grype[reference]@v0.86.1 (reference)  against docker.io/anchore/test_images@sha256:fc6f7a37d7e320f6ff3643d4ec9a2
08adb1462cd16027f045b56563e12bb0461
--------------------------------------------------------------------------------

[kzantow]

👍 much more clear to me 🎉