PET-1192 - Add image subcommand to trivy plugin

[Arabus]

Fixes #888

Had to reorder the args a little because --skip-update belongs to the
image subcommand now

[CLAassistant]

All committers have signed the CLA.

[danielpacak]

@Arabus Thank you for working on this patch. I think we must update Go tests as well. You can check locally with make unit-tests that there are no failures.

[Arabus]

Tests light up all green for me locally so i guess the changes made work. I also updated the comments in the plugin.go to reflect the proper command order. Please have another look when you find the time. 🙏

[codecov]

Codecov Report

Merging #891 (5cead2b) into main (5ab3973) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #891      +/-   ##
==========================================
+ Coverage   65.56%   65.61%   +0.04%     
==========================================
  Files          58       58              
  Lines        6488     6514      +26     
==========================================
+ Hits         4254     4274      +20     
- Misses       1804     1805       +1     
- Partials      430      435       +5     

Impacted Files	Coverage Δ
pkg/plugin/trivy/plugin.go	82.31% <100.00%> (+0.04%)	⬆️
pkg/operator/controller/vulnerabilityreport.go	61.48% <0.00%> (-1.46%)	⬇️
pkg/operator/etc/config.go	75.75% <0.00%> (ø)
pkg/kube/object.go	60.40% <0.00%> (+0.76%)	⬆️
pkg/operator/controller/configauditreport.go	65.88% <0.00%> (+1.47%)	⬆️

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[danielpacak]

LGTM! Thanks you @Arabus !