Add environment variables to sign the release build for the Godot
Android editor and to publish the library to MavenCentral.
If the environment vars are not defined, we do a simple unsigned
`release_debug` build for the Android editor.
Change `config.sh.in` template to use single quotes by default, to
prevent expanding special characters in environment variables.
To publish to MavenCentral, a new `build-android/upload-mavencentral.sh`
script is added. It needs to run after the build using gradle, but we
still want it to be optional and used only when making an official
release, so we copy the compiled sources in the first step.
Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>
The sums are included both in the release folder, and in a separate
`sha512sums` folder in the base directory, to allow verifying that
the sums on the download repository haven't been tampered with.
