multimedia/obuparse: Add Port: Portable single file AV1 OBU parser

Simple and portable single file AV1 OBU parser

Features:

• No allocations; only works on user-provided buffers and the stack.
• OBU header parsing.
• Sequence Header OBU parsing.
• Metadata OBU parsing.
• Tile List OBU parsing.
• Tile Group OBU parsing.
• Frame Header OBU parsing.
• Frame OBU parsing.