Split REST API views by domain ownership and package layout

Description

Apply the domain-ownership audit and package-layout convention to the code, without changing any behavior, so Authorization's package boundaries are visible in the code and not only in documentation.

• Move Admin-Console-shaped endpoints: relocate AdminConsoleOrgsAPIView, ScopesAPIView, TeamMembersAPIView, TeamMemberAssignmentsAPIView, and AssignmentsAPIView into a new rest_api/v1/admin_console/ subpackage.
• Move the temporary flag endpoint: relocate WaffleFlagStatesAPIView into a new rest_api/v1/course_authoring/ subpackage, matching its status as the one exception to Authorization-owned data.
• Keep generic endpoints generic: leave PermissionValidationMeView, RoleUserAPIView, RoleListView, and UserValidationAPIView in views.py, with no reference to any specific consumer's packaging.
• No behavior change: no URL changes, no endpoint-behavior changes; move each view's tests alongside it.
• Cleanup: remove any dead/duplicate module left behind by the split.

Concrete deliverable: rest_api/v1 split into admin_console/ and course_authoring/ subpackages per the ownership/layout ADRs, CI green, no behavior change.