hdr10+: parameter passing for OMX

Add hdr10+ parameter passing to OMX. Metadata is sent to
OMX component via setConfig(). Available output metadata is
notified via onEvent(), and then retrieved via getConfig().

Hdr10+ metadata pass through is added to soft VP9 for testing.

bug: 118507186
test: Locally built DecoderTest in cts that sends
setParameters with input frames when decoding VP9.
Verify the metadata is received on expected output.

Change-Id: I9bb87581a3036f9ae3cc881cbfe1a3c99c8f78b3