Moves filmcraft-avi (storytold/filmcraft@4bec22b) into craft_media::avi.
ByteSource is the crate's trait, Error::Io holds the io::Error, and
Stream::codec_params() maps the FourCC and the WAVEFORMATEX tag to a CodecId.
Adds Container::Avi and tests for the stream, header-size, nesting and
OpenDML index limits.
