Prepare to Add functionality to Replacer interface to restrict setting labels on certain kinds.

[tejal29]

Relates to #1737 and other deploy issues where labels get added to wrong CRDs.

In this PR, i added a Matcher Interface which is used by replacer to replace objects on a manifest key if it is present.

// Matcher is used by Replacer to match object blob to replace based on  a manifest key in the Manifest
type Matcher interface {
	IsMatchKey(key string) bool
	Matches(v interface{}) bool
}

If the manifest object blob contains a match-key and its value is not matched, then we move to the the next Manifest object blob.
In this PR, i have introduced a new interface. This does not change in functionality.
Currently, all replacers namespaceCollector, labelsSetter, imageSaver and imageReplacer use the anyMatcher which match everything.

The next steps for this feature would be

• Add a KindMatcher which will match key kind with values Pod, Deployment and Services (deployed Resources)
• Use the KindMatcher for labelSetter

[tejal29]

Hold, until #2074 is merged since this depends on this.

[ryanbrainard]

@tejal29 Can you explain what the status of this is? I see it was on hold for #2074 and then closed, but it's not clear where it stands now.

[codecov]

Codecov Report

Merging #2060 into master will increase coverage by 0.15%.
The diff coverage is 95%.

Impacted Files	Coverage Δ
pkg/skaffold/deploy/kubectl/labels.go	78.57% <ø> (ø)	⬆️
pkg/skaffold/deploy/kubectl/namespaces.go	82.6% <ø> (ø)	⬆️
pkg/skaffold/deploy/kubectl/images.go	92.18% <0%> (-0.24%)	⬇️
pkg/skaffold/deploy/kubectl/visitor.go	94.11% <100%> (+1.26%)	⬆️
pkg/skaffold/deploy/kubectl/matcher.go	100% <100%> (ø)
pkg/skaffold/initializer/init.go	59.14% <0%> (-2.15%)	⬇️
pkg/skaffold/sync/sync.go	75% <0%> (-0.21%)	⬇️
pkg/skaffold/kubernetes/client.go	40% <0%> (ø)	⬆️
pkg/skaffold/kubernetes/log.go	38.26% <0%> (ø)	⬆️
pkg/skaffold/deploy/status_check.go	63.23% <0%> (ø)	⬆️
... and 10 more

[tejal29]

@dgageot Please take a look. This is ready for review.