[1.7.x] Added new supported languages
[1.7.x] Fixed #23344 -- Removed duplicate docs for file upload settings.

Backport of c7fa27d702 from master
[1.7.x] Fixed #23352 -- Added tests for MigrationGraph.{forwards,backwards}_plan

Backport of be4baaefe2 from master
[1.7.x] Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.

Backport of abd640fbdf from master
[1.7.x] Fixed #22154 -- Added "Built-in" to some class-based views titles.

Backport of 0c9f40f776 from master