[TIMOB-25240] Android: Improve incremental build times

While working on TIMOB-24829 i noticed a few more things in the android build that can be improved, resulting in a faster build time on incremental builds. Compared to the iOS build, which only takes ~5s for incremental builds, the Android build is much slower with ~30-40 sek. Most of the time is spend on recompiling and dexer operations, which are unnecessary if nothing related changed. The Android builder already contains a lot of comments about what can be skipped or cached, but contains no actual code that would do that. The actions in particular are: - Compile java classes (only needs to be done when files in build/android/src or build/android/gen change - Run Proguard (only needs to be done when any java classes changed) - Run dexer (only needs to be done if any libraries changed, any files in build/android/bin/classes have changed or debugging/profiling was toggled. This alone will cut down the android build time by approximately one third. \\ ---- *Final Result:* Below are the performance improvements between Titanium 8.3.0 and 9.0.0 with [kitchensink-v2](https://github.com/appcelerator/kitchensink-v2) on a 15" MacBook Pro 2015 with a solid state drive.

Non-encrypted emulator builds:
- Clean Build: 52s -> 20s  (2.6x faster)
- Incremental: 18s -> 7s   (2.6x faster)

Encrypted device/production builds:
- Clean Build: 53s -> 21s  (2.5x faster)
- Incremental: 50s -> 14s  (3.6x faster)

Notes:
- Benchmarks exclude gradle daemon startup of ~5s which is a one time hit.
- Titanium did not support encrypted incremental builds before. This is new.