Frameworks: Toggle to switch recent panels styles (1/2)

- Allows us to switch between Stock or Slim recent panles;
- Made TRDS work in theme changes;
- Some minor codes improvments;

- default : slimrecent
- code cleanup

This was based on: https://github.com/AOSB/android_frameworks_base/commit/dbb5540884826786bfec9f7ea42a515a09c4094e
credits codex-corp, cristianomatos

Change-Id: I4c4a925103e856c6bd061af594fd34126a226890