Add support for image sequences when creating .otioz files with otioconvert

[darbyjohnston]

It looks like image sequences are not supported when creating .otioz files with otioconvert? I tried converting an .otio file with an image sequence and it looks like the images were not bundled:

> zipinfo SingleClipSeq.otioz
Archive:  SingleClipSeq.otioz
Zip file size: 819 bytes, number of entries: 2
?rw-------  2.0 unx        5 b- defN 23-Jun-10 16:45 version.txt
?rw-------  2.0 unx     3185 b- defN 23-Jun-10 16:45 content.otio
2 files, 3190 bytes uncompressed, 599 bytes compressed:  81.2%

Looking at the code in file_bundile_utils.py there is this comment:

try:
    target_url = cl.media_reference.target_url
except AttributeError:
    # not an ExternalReference, ignoring it.
    continue

It would be nice to add support for image sequences or maybe add a warning that they are being ignored.

[darbyjohnston]

Also it looks like the code in file_bundle_utils.py only calls media_reference(), so maybe multiple media references are also not supported yet?

[meshula]

I believe the state of the discussion is that we'd like such bundling were someone to add it to otioconvert.