Setup output verification tests

[Danielku15]

We want to test for all libraries on all platforms the correct rendering output.

The test we perform is the same on all stages: We generate an alphaTab music sheet via generated test code using the alphaSkia API and visually test it against platform specific reference files. (like the visual regression tests in alphaTab).

• Test the native shared libraries using a test executable linked against them.

  • Goal: ensure produced binaries are generally OK + ensure correct output for the platform
  • Tested variants: linux-x64-shared, macos-x64-shared, windows-x64-shared, linux-x86-shared, macos-x64-shared, windows-x86-shared

• Test the dotnet nuget packages by consuming the nupkgs from a local source.

  • Goal: ensure native libs are correctly consumed and loaded.
  • Tested variants: linux-x64, macos-x64, windows-x64, linux-x86

• Test the Java packages by consuming the maven packages from a local source.

  • Goal: ensure native libs are correctly consumed and loaded.
  • Tested variants: linux-x64, macos-x64, windows-x64, linux-x86

• Test the Node packages by consuming the NPM packages via file:xxx.tgz dependencies.

  • Goal: ensure native libs are correctly consumed and loaded and we have no Node-API compat issues.
  • Tested variants: linux-x64, macos-x64, windows-x64, linux-x86
  • Tested node versions: lts/* and latest

Potential considerations:

• We could compile tests for all linux archs and run the binary via QEMU.
• Via a MAUI DeviceTests(https://github.com/dotnet/maui/wiki/DeviceTests) we could test the rendering output on Android an iOS.