Add Renderer::skipFrame() which should be called when intentionally
skipping frames, for instance because the screen content hasn't changed,
allowing Filament to performance needed periodic tasks, such as
cache garbage collection and callback dispatches.
We also improve the ResourceAllocator cache eviction policy:
- the cache is aggressively purged when skipping a frame
- we aggressively evict entries older than 3 frames
The default Config is now set to a more agressive setting.