libmediautils: move AImageReader_getHGBPFromHandle from libmediandk.

This allows us to remove camerserver's dependency on libmediandk,
thereby reducing its vss increase (brought about due to many of
libmediandk's dependencies, which cameraserver does not need)

Bug: 119582723

Test: mm -j64
Test: showmap <pid of cameraserver> vss before change: 50628
Test: showmap <pid of cameraserver> vss after change: 31256
Test: AImageReaderWindowHandleTest

Change-Id: I8dec6430adda538cb293cdd0d087b9ae1767b900
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>