The first keyframe of the test video can be decoded with these changes.
Raw memory allocations in the Parser have been replaced with Vector or
Array to avoid memory leaks and OOBs.
This allows runtime strings, so we can format the errors to make them
more helpful. Errors in the VP9 decoder will now print out a function,
filename and line number for where a read or bitstream requirement
has failed.
The DecoderErrorCategory enum will classify the errors so library users
can show general user-friendly error messages, while providing the
debug information separately.
Any non-DecoderErrorOr<> results can be wrapped by DECODER_TRY to
return from decoder functions. This will also add the extra information
mentioned above to the error message.
