VP9: Synthesize CSD from frame header

If the CodecPrivate data is missing from the container, use the first
frame's frame header to parse and synthesize the CSD.

This is an update of c9d8dee4
which was reverted. This commit updates the above with support for
cases where the first frame is not a key frame.

Test: atest CtsMediaExtractorTestCases
Test: atest CtsMediaV2TestCases:ExtractorTest
Test: atest CtsMediaV2TestCases:ExtractorUnitTest
Test: atest CtsMediaV2TestCases:DecoderColorAspectsTest
Test: atest CtsMediaV2TestCases:EncoderProfileLevelTest
Test: atest CtsMediaDecoderTestCases:DecoderConformanceTest
Bug: 295804596

Change-Id: I4fd99dcbd736da368c68d802cc2212d4482bc2f0