github-actions, added msys2 section to makefile

[LibreDrip]

• created GitHub-actions for Android, win64, linux64
  • also creates nightly builds
• added msys2 section to Windows-64-bit Makefile
  • msys2 supports getting dependencies through a package manager

Issues/to-do

• linux-nightly not working on Debian stable, compilation only possible with ubuntu-latest libraries
  • working older version is in Debian official repositories, hasn't been updated, with custom changes
    • that same version is used for the flatpak version
• android APK has to be signed, possible through GitHub actions, not done yet
• Windows x86 version possible through GitHub actions, not done yet
• Android build failing if using Java 17
• at some point Windows build complained about git missing, not sure if still needed