CtsMediaBitstreamsTestCases: refactor metric entry format

Log test results in the following format for simpler data analysis:
{
  "path": "path/to/bitstream",
  "codec_name": "omx.decoder.name",
  "status": "unsupported|true|false|crash|timeout"
}

Bug: 30268664
Test: cts-tradefed run cts -m CtsMediaBitstreamsTestCases
Change-Id: I3d6c38dd50f839d422e5a11ec523958889fcd5bf
5 files changed