Implemented according to the specification at https://www.iso.org/standard/69561.html
The 'mhm1' sample entry is registered with MP4RA, which is defined as MHAS encapsulated single stream MPEG-H 3D Audio.
'MHAS' stands for MPEG-H audio stream, which contains encoded audio data and corresponds metadata for decoding.
This patch enables extracting the MHAS bitstream from MP4 and remuxing into MP4.
Signed-off-by: James Almer <jamrial@gmail.com>