frameworks/native: Fixes for AHardwareBuffer, ANativeWindow and ARect docs.

Several of the documentation comments were not being picked up by Doxygen.
Additionally, fixed a problem with an incorrect GL ES equivalent format
being listed for AHARDWAREBUFFER_FORMAT_R8G8B8X8_UNORM.

Bug: 73658203
Bug: 76172636
Bug: 76179340
Test: Not necessary, documentation-only changes.
Change-Id: Ia6bf7853e9eed5ab53616d410f8bd1a6309e47b8