Refactors and reworks the LibraryContentBlock so that its
sync-from-library operations are asynchronous and work with
V2 content libraries. This also required us to make
library_content block duplication asynchronous, as that
involves syncing from the source library.
For the sake of clarity, this PR includes two major method renames:
* update_children(...) -> sync_from_library(...)
* refresh_library(...) -> sync_from_library(upgrade_to_latest=True, ...)
an an XBlock HTTP handler rename:
/refresh_children -> /upgrade_and_sync
There are still a couple issues with import or duplication
of library_content blocks referencing V2 libraries other than
latest. These will be resolved in an upcoming PR.
Part of: https://openedx.atlassian.net/wiki/spaces/COMM/pages/3820617729/Spec+Memo+Content+Library+Authoring+Experience+V2
Follow-up work: https://github.com/openedx/edx-platform/issues/33640
Co-authored-by: Connor Haugh <chaugh@2u.com>
Co-authored-by: Eugene Dyudyunov <evgen.dyudyunov@raccoongang.com>