Add requestor name to GraphicBuffer alloc metadata

Adds a requestor name (usually the BufferQueue consumer's name) to the
metadata that GraphicBufferAllocator stores on allocation so that
`dumpsys SurfaceFlinger` can attempt to attribute buffer usage to the
correct client.

Bug: 30776557
Change-Id: I6e0f346584c871bb3b9d5481f82b697b0475a916