Prefer animation in ImageDecoder.decodeDrawable

Pass down a flag to prefer animation over still images
when decodeDrawble is used. Pass the flag via source
to avoid adding this flag to all create/createFrom/
nCreate method variants. Check the flag only in
native_create when we actually create the decoder.

bug: 120414514
bug: 78868457

Change-Id: I84b4edd0225df9eaa59df8a787bd5902146ab500