[android] Rewrite get-apk-args
Major differences:
- Instead of being a mix of bash and python do it with python only
- Drop support for target from appdata. It's not suitable for serious usage since you can't specify a package name and every app should have an AndroidManifest.xml anyway
- Drop support for target from build spec. It is only used in GCompris and not necessary (!64 (merged))
- Instead of taking a project name it takes a path to the code, which is more flexible and helpful for something I'm working on
- Improved error messages when no AndroidManifest.xml is found or it does not contain the needed metadata
The output format is unchanged