Flutter migration: Build system update

[Izchomatik]

roc-droid Flutter migration child issue.

Restore original gradle features

• [x] Build properties
  • [x] compileSdk, minSdkVersion, targetSdkVersion
  • [x] ndk version
  • [x] jvm version
  • [x] app versionName & versionCode - load from AndroidManifest.xml or from flutter
• [x] Android manifest
  • [x] AndroidManifest.xml should have hard-coded version and version code, and build system should automatically update them
  • [x] permissions (see also here)
  • [x] intents
  • [x] service
• [x] APK building
  • [x] when building APK, check that AndroidManifest and pubspec versions match
  • [x] add project version to APK file name (roc-droid-1.2.3.apk)
  • [x] signing config
• [x] Spotless
  • [x] gradle targets to run spotless (check & format)
  • [x] doit targets
• [x] tag.py
  • [x] move to script/make_tag.py
  • [x] extract update_version.py