Move all sitemaps / rss feeds into a better workflow

[MildTomato]

Chore

Describe the chore

Perhaps move the RSS feed and Sitemap generation into a GitHub action.

Currently what is happening is .xml files are appearing in git commits as they are being generated on npm run build locally.

[MildTomato]

Example of PR needed to keep things up to date
#12463

[brandongregoryscott]

Hey @MildTomato, started taking a look at this - do the apps/docs and apps/www sites need to be built before running the generate-sitemap.mjs scripts? I'm not sure how those are built/deployed - not seeing any workflows that seem to run the build commands and it seems you need some environment variables set for it to build properly in CI.

Edit: Nevermind about that - could've sworn I had a CI failure from attempting to build apps/docs or apps/www but I swapped it back to do a full build and seems to be running now.

I have a proof-of-concept generate-sitemap workflow working on my fork (PR example https://github.com/brandongregoryscott/supabase/pull/1/files) that leverages the Create Pull Request Github Action to commit, push & PR changed XML files in the apps/www or /apps/docs directories.

[MildTomato]

POC that @brandongregoryscott did

[MildTomato]

This was closed in favour of pursuing a solution keeping sitemaps and rss feeds out of version control, and have them created at build time