Improve weekly spec drafts updating GitHub Actions workflow

[ddbeck]

Working with these is a bit annoying. I can never remember the steps needed to handle merging with main. I ended up making a few changes to the workflow file to try to make this more approachable. Changes include:

• Running dist as part of npm run update-drafts. This is the single biggest headache I was having.
• Explicitly deleting and adding files, so it's clearer what files this workflow is meant to update.
• Using a label to identify generated PRs (this will make it easier for me to review these PRs alongside dependabot changes).
• Using the peter-evans/create-pull-request to do the commit, instead of a custom step and committer config.
• Linking to the workflow file from the pull request body.

[Elchi3]

Hard to test but the reasoning sounds good to me. One optional comment.

[ddbeck]

OK, we'll find out how much I broke this on Monday. 😅

[ddbeck]

I found the first problem even sooner. #1735