Factor out code into smaller methods to be used by repomaker
This MR does not change any existing functionality. It only factors code out into smaller methods. This allows for consumers of fdroidserver to re-use more code and allows simplifications such as this.
These changes have been made:
- reading and writing to cache happens now in dedicated methods
- applying information from latest APK to app (and getting latest updated date) is now its own method
- the method that generates a repo key now returns the public key and the repo fingerprint