C2SoftOpusDec: Add support for decoding single CSD

If first CSD contains additional bytes, those are decoded
based on markers present.

C2 encoder plugin sends CSD in this format, so decoder is updated to
support such input.

C2 decoder also continues to support three different CSDs in sent in
the legacy format (OpusHead in first CSD, followed by two CSDs of 8 bytes
to signal CodecDelay and seek pre-roll)

Bug: 115576456
Test: cts-tradefed run commandAndExit cts-dev -m CtsMediaTestCases \
 -t android.media.cts.DecoderTest

Change-Id: I089acbd2dddd36175c1e92455e488719a0e3a143