Tweaks to channel ordering for import from channels

[rtibbles]

Summary

Description of the change(s) you made

• Sets a default ordering on the channel endpoint.
• Adds and uses custom ordering for import fetches.

Manual verification steps performed

1. Check ordering on import from channels for content library - should be sorted by name
2. Check ordering on import from channels for 'my channels' - should be sorted by last modified
3. Check ordering on channel list pages that this has not changed

Screenshots (if applicable)

My channels - last modified sort:

Content library - name sort:

My channels page - last modified sort:

Content Library - name sort:

Does this introduce any tech-debt items?

Might want to come back and cleanup how we are handling ordering slightly - Kolibri handles it a bit better, and leaning on that would allow us to sort by multiple fields from the frontend.

References

Makes updates suggested here: #3592 (comment)

[marcellamaki]

This looks good. Tested all scenarios and working as expected.