GitHub action to sync branches

[flanakin]

⚠️ Problem

Merges are currently manually run, which can lead to branches going stale and complicating merges later.

🛠️ Solution

Create a GitHub action to merge dev to all feature branches when there are updates.
If there's a merge conflict, create an issue to track the out-of-sync feature branch.
If an out-of-sync issue already exists, add a comment instead of creating a new issue.

ℹ️ Additional context

This can leverage the Merge-DevBranch * script to execute merge but will need to add support for creating issues when a branch fails to merge. We can also split those out as separate tasks, if someone wants to knock out the simple merge script as an easy win.

🙋‍♀️ Ask for the community

We could use your help:

1. Please vote this issue up (👍) to prioritize it.
2. Leave comments to help us solidify the vision.