Update sorting of channel items and fix erroneous use of sortBy

[rtibbles]

Summary

Description of the change(s) you made

• sortBy was being used under the assumption that it could be passed field names prefixed with - to reverse the ordering. This is not the case.
• Updates these uses of sortBy to use orderBy with an additional array of asc/desc to specify the order of sorting.
• Fixes ordering on the catalog list page as the ordering from the API is lost once items are retrieved from vuex - resorts using the name parameter.

Manual verification steps performed

Checked sorting by modified time on My Channels page.
Checked sorting on Catalog list page.

Screenshots (if applicable)

Update to my channels - all channels shown in descending order of last modified:

Update to catalog list - all channels now properly sorted by name when displayed:

References

Fixes #3559
Fixes #3294

[MisRob]

Thank you, @rtibbles. I have some issues with Studio localhost, so I wasn't able to preview changes myself, but at least checked code and it's looking good to me.

[pcenov]

@rtibbles do you think that this fix should be applied to the "Import from other channels" modal as well?

[rtibbles]

I'll investigate to see how sorting is happening there - I did update all the code errors in this PR, but it might need another tweak there.