Course-to-Library Import: Drop old implementation

[kdmccormick]

We had tried to implement the initial Import API for Teak, under the app name import_from_modulestore. We decided not to launch for Teak.

For Ulmo, we've taken the opportunity to start fresh, under the app name modulestore_migrator (#36873).

This means we need to drop the import_from_modulestore app. PRs:

1. feat!: Drop import_from_modulestore app (1/3 -- code only) #37239
2. feat!: Drop import_from_modulestore app (2/3 -- models) #37240
3. feat!: Drop import_from_modulestore app (3/3 -- uninstall app) #37241

This 3-step process is based on https://openedx.atlassian.net/wiki/spaces/COMM/pages/1051361376/Removing+a+Djangoapp+from+an+existing+project

[kdmccormick]

FYI @cmltaWt0 , I'll be getting these merged soon so that you we can merge modulestore_migrator without worry about the old code.

[kdmccormick]

@cmltaWt0 Do you mind reviewing these 3 PRs?

[cmltaWt0]

@cmltaWt0 Do you mind reviewing these 3 PRs?

Sure, will do tomorrow.

[UsamaSadiq]

Approved the first PR in the list. Assuming the failures in the 2nd and 3rd PR will be fixed when the 1st one is merged. I haven't looked deep into the 2nd and 3rd PR for now.

[kdmccormick]

Thanks!