Support role assignments for keys (courses, and others) that do not exist yet

[mariajgrimaldi]

Description

In the course rerun flow, we may need to associate access with a destination_key before the destination course fully exists. Today, openedx-authz expects the course to already exist, so the rerun flow needs authz-specific branching to avoid assigning the role too early.

Supporting this in openedx-authz could reduce the number of places where we need to check the authz toggle directly and avoid adding more branching logic between the legacy and authz paths.

The immediate course rerun issue is being handled in: openedx/openedx-platform#38840

[bradenmacdonald]

If/when this is implemented, most of the changes from openedx/openedx-platform#38840 could be reverted, to simplify the code.

[efortish]

Hello @BryanttV

Here is the PR can you please take a look of it?

• feat: support role assignment for scopes that don't exist yet #369