qtdemux: Add support HEIF compatible media
HEIF file format is a variant of ISOBMFF for image (or image sequence). Although HEIF files are compatible with ISOBMFF, there should be special concern since 'moov' atom is not mandatory for that specification. For instance, top-level 'meta' atom can take the role of moov. Also, top-level 'meta' and 'moov' can co-exist in a file.