Release automation improvements

[BrynCooke]

Tasks

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1. Update RELEASE_CHECKLIST to instruct to use the xtask command or the CircleCI approval jobs to do a release.
2. Make release prepare use a non-protected branch for preparation.
3. Make helm chart versions auto-increment or maybe track the router version.
4. Make release PR target dev (for easy reviewing)
5. Make everything work from Circle CI using a workflow.
6. Add linting policy to all PRs that ensures CHANGELOGs meet formatting requirements.
7. Ensure links to issues and PRs are not 404 / wrong (effectively, if the release script is going to fail because something it's detecting and trying to add to a milestone is not a PR then we should fail earlier in the pipeline.)
8. Only add issues and PRs to milestones if they are in the title or the "By line" of the changelog entry, not if they're just referenced somewhere in the Changelog text.
9. Don't include empty selections from the NEXT_CHANGELOG when moving them to the CHANGELOG. (e.g., don't put Breaking at the top of every release)
10. Ensure that federation-version-support.mdx is indicating the correct version of Federation that is included in the Router.

Release Steps might be

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1. Make release perform:
2. Re-target PR to main branch
3. Merge the PR
4. Create release branch from main
5. Do the tagging stuff
6. Copy the changelog to the description for the Github Reelase.
7. Remove the version and date line when doing so to not be repetitive.
8. When doing so, replace [@username](https://github.com/username) with just @username to ensure the "Contributors" feature picks up those @-mentions and says "6 contributors" instead of just saying apollo-bot
9. Make a PR merging main back into dev (Use the API to set this as an auto-merge PR that uses REAL MERGE NOT SQUASH 🎃 (Is this possible?))

[abernix]

I added a few more things to this list, but I'm not sure how many of them on here are already done (or if this issue was meant to be closed already?)

[BrynCooke]

They all need to be tackled. Hopefully most won't be a heavy lift and we can do these incrementally each time we release.

[abernix]

Cool! I added a couple further points above and agree on incrementality. This was a huge improvement that I was very happy to find out about today, so thanks for getting it started!