Add deployment health check implementation

[tejal29]

This PR depends on #2338 to go in.

This in addition to add status-check flag covered in #2338, does the following

• implements the status check for deployment by

  • get a list of skaffold deployed deployments using label -l app.kubernetes.io/managed-by=skaffold-<version>
  • for every deployment, get the spec.progressDeadline if set or set it to 10 minutes.
  • run kubectl rollout status after every 600 ms which is the default polling period.
  • finally either pass or fail depending on if the deployment was stabalized

• Add unit tests

• Add integration tests.

TODO:

• Add pod stabilization: PR here Add pods stability for health check. #2374
• update deployment state, so in case of "sync" for invalid deployments in dev loop, actually perform a build.

[codecov]

Codecov Report

Merging #2359 into master will decrease coverage by <.01%.
The diff coverage is 68.35%.

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/flags.go	100% <ø> (ø)	⬆️
pkg/skaffold/deploy/kubectl/cli.go	96% <100%> (+0.44%)	⬆️
pkg/skaffold/deploy/status_check.go	66.17% <66.17%> (ø)
pkg/skaffold/runner/runner.go	70.67% <66.66%> (-0.65%)	⬇️

[priyawadhwa]

lgtm overall!

[priyawadhwa]

LGTM! Just a nit and small questions