cli/daemon/apis/test: support to load docker images without name

[fuweid]

Signed-off-by: Wei Fu fuweid89@gmail.com

Ⅰ. Describe what this PR did

For the docker image format, the tar file will contain the image
reference information. For this case, when we load the docker images, we
should not set the image name. If there are too many images and you just
want to load one of them, you can set the name.

Ⅱ. Does this pull request fix one issue?

fixes #2787

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

added

Ⅳ. Describe how to verify it

CI

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Merging #2837 into master will increase coverage by 0.07%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #2837      +/-   ##
==========================================
+ Coverage      69%   69.08%   +0.07%     
==========================================
  Files         285      285              
  Lines       17824    17828       +4     
==========================================
+ Hits        12300    12316      +16     
+ Misses       4119     4108      -11     
+ Partials     1405     1404       -1

Flag	Coverage Δ
#criv1alpha2_test	38.99% <0%> (-0.01%)	⬇️
#integration_test_0	36.6% <0%> (-0.01%)	⬇️
#integration_test_1	35.31% <33.33%> (-0.01%)	⬇️
#integration_test_2	36.54% <0%> (+0.02%)	⬆️
#integration_test_3	35.47% <66.66%> (+0.04%)	⬆️
#node_e2e_test	34.8% <0%> (-0.02%)	⬇️
#unittest	28.56% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
apis/server/image_bridge.go	75.4% <ø> (+1.21%)	⬆️
daemon/mgr/image_load.go	56.52% <66.66%> (+15.34%)	⬆️
daemon/logger/crilog/log.go	79.71% <0%> (-2.9%)	⬇️
daemon/containerio/io.go	72.81% <0%> (-1.95%)	⬇️
cri/ocicni/cni_manager.go	58.49% <0%> (-1.89%)	⬇️
ctrd/container.go	53.53% <0%> (-0.39%)	⬇️
cri/v1alpha2/cri.go	69.31% <0%> (ø)	⬆️
daemon/mgr/container.go	60.14% <0%> (+0.62%)	⬆️
daemon/mgr/spec_linux.go	80.21% <0%> (+1.06%)	⬆️
cri/ocicni/netns.go	60.81% <0%> (+2.7%)	⬆️
... and 1 more

[rudyfly]

LGTM