Add WindowContextCleaner

Thie CL adds a cleaner to clean up WindowContext vs overriding fianlize.
It give system server more time (5X original timeout) to detach
WindowContext.

Fixes: 339727951
Test: atest WindowContextTest
Flag: com.android.window.flags.clean_up_window_context_with_cleaner
Change-Id: I2ef4a7f1601aa16f8130a6965e84852b04aa283c