Automate release pages

[LWinterberg]

Currently, releases need to be updated by hand via assets/js/releaseData.js. Additionally, alphas and betas aren't represented at all. We could automate this.

Alphas

• Get an API which gets the latest build from Github and offers it to download (similar to https://github.com/oprypin/nightly.link )
• Do the same for the qt branch once that's testing-ready
• Create a /builds page on which they can live (similar to https://builder.blender.org/download/daily/)

Betas

• Create a GH action which publishes a beta release on Github
• and enables temporary elements to the homepage pointing towards the beta

Releases

• Create a GH action which publishes releases to
  • winget
  • Github releases
  • musehub
  • Fosshub
  • MS store
  • (if legally possible) Apple App store
  • (if we want to maintain it) Snapcraft
  • (if we want to maintain it) Flathub
• updates releaseData.js
• and hides the temporary beta element from the homepage