[deps] Bump k8s and docker client library deps

[nkubala]

Major dep updates:

• Kubernetes client libraries bumped from 0.18.1 to 0.19.3 (k8s.io/apimachinery was already 0.19.2)
• Docker client library changed from v1.14.0 to v20.10.0-beta1
  • This is required by moby/buildkit: ref vendor: update docker/docker and moby/sys docker/cli#2835
• go-containerregistry updated from v0.1.1 to v0.1.4

Required code updates:

• All calls to various k8s client libraries consume a context now, so this was plumbed through in many places

NOTE: This change is currently incorporating changes from a personal fork of buildpacks/pack, as there were unresolvable dependency incompatibilities. This PR should not be merged until buildpacks/pack#960 is upstreamed, and the dependency replacement is removed.

This change is non-functional.

[codecov]

Codecov Report

Merging #5038 (2562e93) into master (e91c8e6) will not change coverage.
The diff coverage is 48.78%.

@@           Coverage Diff           @@
##           master    #5038   +/-   ##
=======================================
  Coverage   72.43%   72.43%           
=======================================
  Files         368      368           
  Lines       12971    12971           
=======================================
  Hits         9396     9396           
  Misses       2886     2886           
  Partials      689      689           

Impacted Files	Coverage Δ
pkg/diag/validator/pod.go	1.22% <0.00%> (ø)
pkg/skaffold/build/cluster/cluster.go	25.80% <0.00%> (ø)
pkg/skaffold/build/cluster/kaniko.go	22.36% <0.00%> (ø)
pkg/skaffold/build/cluster/logs.go	15.78% <0.00%> (ø)
pkg/skaffold/deploy/helm/deploy.go	70.50% <0.00%> (ø)
pkg/webhook/kubernetes/deployment.go	0.00% <0.00%> (ø)
pkg/webhook/kubernetes/service.go	0.00% <0.00%> (ø)
pkg/skaffold/build/cluster/secret.go	40.32% <28.57%> (ø)
pkg/skaffold/deploy/label/labels.go	45.58% <33.33%> (ø)
pkg/skaffold/kubernetes/wait.go	45.31% <33.33%> (ø)
... and 7 more

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[MarlonGamez]

that's a whole lotta context