Reset State on Build

[tejal29]

Relates to #2940
Reset Build state when a Build Trigger is received or via Control API, a build request is sent.

Description

User facing changes

yes.

Before

1. skaffold Build from master, run with RPC.

cd examples/getting-started
skaffold dev --default-repo=gcr.io/tejal-test --trigger manual --enable-rpc 

2. Change a file

3. Curl the state

 curl localhost:50052/v1/state | jq
{
  "buildState": {
    "artifacts": {
      "gcr.io/tejal-test/gcr.io/k8s-skaffold/skaffold-example": "In Progress"
    }
  },
  "deployState": {
    "status": "Complete"
  }
}

After

1. skaffold Build from master, run with RPC.

cd examples/getting-started
skaffold dev --default-repo=gcr.io/tejal-test --trigger manual --enable-rpc 

2. Change a file

3. Curl the state

 curl localhost:50052/v1/state | jq
{
  "buildState": {
    "artifacts": {
      "gcr.io/tejal-test/gcr.io/k8s-skaffold/skaffold-example": "In Progress"
    }
  },
  "deployState": {
    "status": "Not Started"
  },
  "statusCheckState": {
    "status": "Not Started"
  }
}

Next PRs.

• Reset State on Deploy

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes unit tests
• Mentions any output changes.
• Adds documentation as needed: user docs, YAML reference, CLI reference.
• Adds integration tests if needed.

See the contribution guide for more details.

Double check this list of stuff that's easy to miss:

• If you are adding a example to the examples dir, please copy them to integration/examples
• Every new example added in integration/examples dir, should be tested in integration test

Reviewer Notes

• The code flow looks good.
• Unit test added.
• User facing changes look good.

Release Notes

Describe any user facing changes here so maintainer can include it in the release notes, or delete this block.

[codecov]

Codecov Report

Merging #2944 into master will increase coverage by 0.02%.
The diff coverage is 92.3%.

Impacted Files	Coverage Δ
pkg/skaffold/server/endpoints.go	0% <0%> (ø)	⬆️
pkg/skaffold/runner/dev.go	67.64% <100%> (+0.32%)	⬆️
pkg/skaffold/event/event.go	89.37% <100%> (+0.78%)	⬆️