* feat: Refactor out non REST portions of enrollment api from enrollment POST method
For use with edx-enterprise to avoid making REST calls for bulk enrollment and other use cases
ENT-4746
* feat: Remove unused test
Testing is covered by test_views
* refactor: isort
isort fixes
* docs: ADR for why this change
ADR
ENT-4746
* test: Fix test failure by restoring course_id to correct object
* test: Test fix
* refactor: pylint fixes
* refactor: raise from to avoid pylint error
* refactor: Start to work toward a util in enterprise_support instead of refactoring this endpoint
* feat: Add util function in enterprise_support to eventually handle enrollment, only used by bulk enrollment for now
* feat: One more revised idea, this time low risk in edx platform and also helps address enterprise specific flow. testing pending
* feat: syntax and unused constant
* feat: Restore view and add new util function to use in edx-enterprise instead
* feat: breakpoint
* unused import
* feat: don't fail on existing enrollment
* docs: ADR update
* docs: docstring minor update
* test: unit test add_user_to_course_cohort
* refactor: imports
* feat: remove unused error classes
* refactor: lint
* test: Test cases
* test: Two more tests for negative cases
* feat: missing init.py file
* test: Fix tests to use correct user mock
* unused import
* refactor: Review feedback, test fixes, needs rebase now
* feat: rebase changes
* feat: keep audit_log with similar logic as in the view
* refactor: Review feedback, test constant usage
