Add skaffold inspect command

[gsquared94]

Related: #5758

Description

• Adds command skaffold inspect
• Implements skaffold inspect modules list

[codecov]

Codecov Report

Merging #5765 (b2e078e) into master (4106c53) will decrease coverage by 0.10%.
The diff coverage is 97.87%.

@@            Coverage Diff             @@
##           master    #5765      +/-   ##
==========================================
- Coverage   70.87%   70.76%   -0.11%     
==========================================
  Files         421      432      +11     
  Lines       16087    16242     +155     
==========================================
+ Hits        11401    11494      +93     
- Misses       3850     3902      +52     
- Partials      836      846      +10     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/inspect_modules.go	87.50% <87.50%> (ø)
cmd/skaffold/app/cmd/cmd.go	63.80% <100.00%> (+0.22%)	⬆️
cmd/skaffold/app/cmd/commands.go	81.63% <100.00%> (+1.63%)	⬆️
cmd/skaffold/app/cmd/config.go	100.00% <100.00%> (ø)
cmd/skaffold/app/cmd/inspect.go	100.00% <100.00%> (ø)
pkg/skaffold/inspect/modules.go	100.00% <100.00%> (ø)
pkg/skaffold/inspect/output.go	100.00% <100.00%> (ø)
pkg/skaffold/parser/config.go	79.68% <100.00%> (+0.99%)	⬆️
pkg/skaffold/util/tar.go	50.66% <0.00%> (-5.34%)	⬇️
cmd/skaffold/app/cmd/render.go	44.44% <0.00%> (-1.99%)	⬇️
... and 28 more

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[MarlonGamez]

code looks good! just have a questions about organization

[MarlonGamez]

do we want to move this into a subpackage? A bit worried that we may clutter up the cmd/ dir even more with these subcommands

[gsquared94]

I took a stab at it but it's very convoluted the way command builder, command definitions and command instantiations interact along with common and specific flags instantiations. I'll look at that separate from this PR.