[v2] feat: Add kubectl renderer

[tejal29]

In PR, we are adding a kubectl renderer so user's just relying on kubectl or helm don't have to depend on kpt.

The kubectl renderer is invoked when

1. there is no validator is defined
2. no kpt config defined and
3. No transformer defined.

if config.Validate == nil && config.Transform == nil && config.Kpt == nil {
		return kubectl.New(config, workingDir, hydrationDir, labels)
	}

Description of changes

1. Move skaffold/render/renderer/renderer.go → pkg/skaffold/render/renderer/kpt/kpt.go and rename renderer.SkaffoldRenderer to renderer.kpt.Kpt
2. Move skaffold/render/renderer/renderer_test.go → pkg/skaffold/render/renderer/kpt/kpt_test.go
3. Add renderer.kubectl.Kubectl in pkg/skaffold/render/renderer/kubectl/kubectl.go which uses the already implemented generated.Generator to read k8s manifests, add labels to these manifests and write them to a hydration dir
4. Create a render util GenerateHydratedManifests which calls generated.Generator.Generate to read k8s manifests, add labels to these manifests and write them to a hydration dir. This method is used in both Kpt and Kubectl renderer.

Things to do next

• Remove Render from deployer.Deploy interface
• Remove --skip-render flag as rendering will always happen
• Remove manifests from v1.KubectlDeploy section.
• Support helm rendering i.e Implement backwards-compatible "legacy" helm deployer #6720

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (v2-v1.36.0@c35b5d1). Click here to learn what that means.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             v2-v1.36.0    #7118   +/-   ##
=============================================
  Coverage              ?   67.61%           
=============================================
  Files                 ?      557           
  Lines                 ?    26552           
  Branches              ?        0           
=============================================
  Hits                  ?    17954           
  Misses                ?     7310           
  Partials              ?     1288           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c35b5d1...95de416. Read the comment docs.

[tejal29]

copied over to GenerateHydratedManifests in renderer/util package

[MarlonGamez]

Hey @tejal29 , can we rebase this on v2-1.36.0?

[tejal29]

Hey @tejal29 , can we rebase this on v2-1.36.0?

done!

[MarlonGamez]

@tejal29 looks like there are some linter errors but besides that I think this is good !

[tejal29]

@tejal29 looks like there are some linter errors but besides that I think this is good !

done!