[BD-14] Work notes

4.0a

4.0c

4.1a

4.1b

[Investigate] Update randomized content xblock to be able to use content libraries V2 along with legacy v1 libraries

https://github.com/openedx/edx-platform/pull/30615

• filtering by problem type works for V2 the same as for V1 NOTE: this can't be done for now because the v2 library problems are not divided by types

• Source Xblock performs resaving of the blockstore blocks into the modulestore to use them in the course.

• as for now, the random xblock saves the V1 lib blocks as its own children with new ids.

• LibraryLocator is not applicable for v2 libraries (they are not modulestore instances at all)