Move Syncer into Deployer

[nkubala]

Related: #5813

Description

This change moves the Syncer object from the Runner into the Deployer, since the syncing behavior is implicitly tied to the underlying Deployer implementation. See #5809 for a more detailed description of why we need to do this.

This change adds one method to the Deployer interface:

type Deployer interface {
  ...

  GetSyncer() sync.Syncer
}

The GetSyncer() method is used by the Runner to retrieve theSyncer implementation and actually orchestrate that behavior in the dev loop.

[codecov]

Codecov Report

Merging #6053 (592c3bd) into master (9ebb319) will decrease coverage by 0.04%.
The diff coverage is 48.38%.

@@            Coverage Diff             @@
##           master    #6053      +/-   ##
==========================================
- Coverage   70.31%   70.27%   -0.05%     
==========================================
  Files         471      473       +2     
  Lines       18077    18101      +24     
==========================================
+ Hits        12711    12720       +9     
- Misses       4434     4449      +15     
  Partials      932      932              

Impacted Files	Coverage Δ
pkg/skaffold/deploy/deploy_mux.go	58.00% <0.00%> (-3.71%)	⬇️
pkg/skaffold/runner/v1/dev.go	72.30% <0.00%> (ø)
pkg/skaffold/runner/v1/runner.go	0.00% <ø> (ø)
pkg/skaffold/sync/syncer_mux.go	0.00% <0.00%> (ø)
pkg/skaffold/sync/types.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/skaffold/deploy/helm/deploy.go	78.22% <50.00%> (-0.23%)	⬇️
pkg/skaffold/deploy/kpt/kpt.go	80.92% <50.00%> (-0.21%)	⬇️
pkg/skaffold/deploy/kubectl/kubectl.go	68.31% <50.00%> (-0.19%)	⬇️
pkg/skaffold/deploy/kustomize/kustomize.go	74.34% <50.00%> (-0.33%)	⬇️
pkg/skaffold/sync/provider.go	71.42% <71.42%> (ø)
... and 3 more

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[MarlonGamez]

lgtm