Remove CMP Enrollment Attributes and Old Style REMOTE_USER Enrollment

As of 3.1.0, EnvSource and CoEnrollmentAttribute::default_env replace CMP Enrollment Attributes.

1. Remove CmpEnrollmentAttribute and any references, including CMP level configuration.
   1. Remove "Enable Organizational Attributes Vis CO Enrollment Flow" in CMP Settings
2. Remove old style sync on login from UsersController.
3. Remove "Ignore Authoritative Values" from CoEnrollmentFlow and CoEnrollmentAttribute, including configuration views and petition implementation.
4. Update CoPetitionsController::beforeRender.
5. Update CoEnrollmentAttribute->mapEnvAttributes.

Also, remove support for "old style" REMOTE_USER based Enrollment Flows. (Flows should use EnvSource instead.)

1. Remove support for storing the login identifier from CoPetitionsController::execute_collectIdentifier.
   1. This should invalidate CO-460
2. Remove support for Org Identity attributes and Copy-To-CoPerson? (CO-862)