feat: pr watcher for Grove

Description

Adds PR watching support to Grove for edx-platform forks.

When the command is invoked it will check the provided EDX_PLATFORM_FORKS and GITHUB_USERNAMES for any open or closed pull requests.

• If the pull request is open
  • Trigger the creation of a new instance if it doesn't exist in the grove-template fork
  • Otherwise trigger the update pipeline
• If the pull request is closed
  • run the destroy pipeline if it's still running (by checking if the namespace exists).

Some assumptions and notes:

• Instances names are of the format pr-{pr-number}-{fork-hash} so that operators can watch more than one fork and not have collisions
• The settings block is unchanged from Ocim's
• The code in github.py is almost a direct copy of Ocim's.
• When an instance is created/updated a PR_WATCHER key is added to grove.yml to keep track of what was last deployed.
• Due to time constraints, only a few integration tests are added.
• The PR watcher CRON is set to run once per hour. It is not enabled on the test environment.

Testing instructions

Test the create:

I've created a test edx-platform fork https://github.com/keithgg/edx-platform and added keithgg and gabor-boros to the list of allowed users.

• Create a PR against that repo and be sure to add a Settings block (even if empty).
• Run the function: curl --insecure -u admin:pass https://openfaas.kgcluster.opencraft.hosting/function/pr-watcher
• You will see the pipeline running to create your instance on https://gitlab.com/opencraft/devstacks/keith/grove-do/-/pipelines
• Example: https://gitlab.com/opencraft/devstacks/keith/grove-do/-/pipelines/703939976

Test the update

• Make a change to your PR and run the curl command again.
• The update pipeline for your PR will be triggered.

Test the destroy

• Close your PR
• The destroy pipeline for your PR should be triggered
• Example: https://gitlab.com/opencraft/devstacks/keith/grove-do/-/pipelines/703913703

Checklist

If any of the items below is not applicable, do not remove them, but put a check in it.

• All providers include the new feature/change
• All affected providers can provision new clusters
• Unit tests are added/updated
• Documentation is added/updated
• The TOOLS_CONTAINER_IMAGE_VERSION in ci_vars.yml is updated
• The grove-template repository is updated