Update shrinkwrap on PR.

[hxtree]

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

Dependobot, Synk, etc. PR as not actionable because those utils do not perform rush update to update the shrink wrap. This makes it time consuming to accept package recommendations and see if the failure is related to dep undate failing.

This step is also often missed by humans as well.

Describe the solution you'd like
A clear and concise description of what you want to happen.

On PR run github action to checkout branch, perform desired commands, and push to branch. This should be possible using gh.

• name: Checkout PR env: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
  run: |
  #checkout branch
  gh pr checkout ${{ github.event.pull_request.number }}

rush update
rush api

etc

push changes

env: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} run: git push

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[hxtree]

Change should be made. On PR open rush update runs and commit changes back to repo. See codegen workflow. Feel free to reopen if issues arrises.