FrameCaptureLayer: Migrate away from IGBC

We're no longer supporting client use of IGBP/IGBC. This CL replaces
usage in FrameCaptureLayer.h/cpp with BufferItemConsumer.

BYPASS_IGBP_IGBC_API_REASON=warren buffers

Bug: 393639153
Flag: com.android.graphics.libgui.flags.wb_media_migration
Test: atest MediaMetadataRetrieverTest seems to use this.
Change-Id: I1a45201d8eb6b6dc16faa6c7e2ca0e8c115ef87a