Reuse frame decoder for sequential frame retrievel

Allow sequential frame retrieval to reuse the decoder without
re-init and re-seek.

Get rid of IMediaMetadataRetriever api that retrieves multiple
frames at a time, this method could hold up more memory than
what's needed, because the client side has to copy the frames
to a separate set of bitmaps anyways.

This change is needed to support animation Drawbles efficiently
which typically get one frame at a time.

bug: 120414514
test: cts MediaMetadataRetrieverTest, local tests that tests MetadataRetriever thumbnails

Change-Id: I09924408b51bc7491fc5dee121dce9a286c5911f