Mod auto-download (MAD) tracker

[Alystrasz]

While there is some progress on the feature, multiple bugs must be fixed before it can be publicly released.

Issues

• Fetch manifesto when trying to download a mod (and not before)
  • Launcher PR: Only fetch MAD manifesto on server join NorthstarLauncher#751
  • Mods PR: Only fetch MAD manifesto on server join NorthstarMods#821
• Revert Add a generic "JoinServer" function NorthstarMods#693 via Revert "Add a generic "JoinServer" function" NorthstarMods#828
• Update manifest structure to allow for download sources other than Thunderstore
  • Verified Mods PR: feat: Adjust JSON structure to allow for other mod sources (but better) VerifiedMods#41
  • Launcher PR: Adjust for restructured verified-mods.json NorthstarLauncher#748
• Handle multiple mod versions NorthstarLauncher#757
  • Launcher PR: fix: Multiple mod versions NorthstarLauncher#758
  • Mods PR: fix: Multiple mod versions NorthstarMods#824
• Cancellable install
  • Launcher PR: feat: Make MAD process cancellable NorthstarLauncher#815
  • Mods PR: feat: Make MAD process cancellable NorthstarMods#865

Fixes

• Game state is not correct when MAD process fails (Issue on mod download failure NorthstarLauncher#756)
  • fix: Rework MAD cleanup handles NorthstarLauncher#817