Summarize dgoss results after execution completes

[ianpittwood]

Closes #102
Follows #122

• Model Goss's JSON output as a series of Pydantic models.
• Summarizes dgoss results in a rich.Table by image name, version, and type with the total test duration and number of successful, failed, and skipped tests.
• Print condensed summary of any failed tests split up by their associated unique image identifier.
• Modify error identification and collection behavior in dgoss
  • No longer propagate errors via raise, instead return them as part of a tuple with the test results.
  • If dgoss exits non-zero, assume it's due to test failures if the command produced a valid JSON output.
  • If dgoss exits non-zero and output cannot be parsed as JSON, consider the command to have experienced a runtime error. Create and collect a BakeryToolRuntimeError to return with the commmand.

This approach has some shortcomings we'll need to consider:

• This implementation locks us into JSON outputs to the end user. goss cannot produce multiple result outputs. If we wish to allow other result outputs, we will need to heavily modify our implementation to expect a variety of different output formats or we will need to convert the JSON into other formats ourselves. I assume team's may want a more common standard reported back, such as JUnit, so we will need to consider how/if we want to perform that conversion or if we should just ignore summarizing results in the CLI.
• Result summary output is not suppressed by --quiet. We may want to consider if it should be.

[github-actions]

Test Results

301 tests   299 ✅  1m 9s ⏱️
  1 suites    2 💤
  1 files      0 ❌

Results for commit 8be45c2.

♻️ This comment has been updated with latest results.

[bschwedler]

Thank you for doing this! The output of bakery run dgoss is much cleaner output is much easier to look through now:

[bschwedler]

It could be useful to include the list the skipped tests when the --verbose flag is set.

This also makes me think about whether we should break up the tests into sections or files that are included conditionally instead of peppering this everywhere

    skip: {% raw %}{{ if eq .Env.IMAGE_TYPE "min" }}true{{ else }}false{{ end }}{% endraw %}