Include DMG for all relevant MacOS Versions into a release

[hessenfarmer]

Is your feature request related to a problem? Please describe.

See https://www.widelands.org/forum/topic/5957
as our policy says that we support all OS versions supported by the vendor we should include them for a release.
It is ok to restrict the test suite runs to 2 of them but for the release we should try to deliver all versions that are supported by the github build environment.

Describe the solution you'd like

have a new build script that is only triggered for the release, which creates and tests all macOS dmg packages supported by the github build environment.
Namely these are macOS12 and macOS13 versions for arm and macOS13 and macOS14 for intel architectures

[bunnybot]

Mirrored on Codeberg as #CB4808.

[hessenfarmer]

maybe we should aim for universal binaries as described in this article
https://developer.apple.com/documentation/apple-silicon/building-a-universal-macos-binary
however I am unsure how to manage that the correct dylibs get assembled in the dmg

@widelands/developers has anybody else then @klaus-halfmann the possibility to try this on a local machine?