[BUG] Mocking submitted libraries fail

[gregbell26]

Description

Issue

If a library is submitted and the autograder needs to mock something in that library, the mocks fail to apply.

Additionally, if mocks are requested, when Dill serializes it, it requires a reference to the library, which does not exist in the parent.

Steps to recreate

Add a helper library.
Attempt to mock something from it.

Solution

The autograder should be able to mock methods in submitted libraries without issue.
Ideally this should be done with env mocks, not a module mock.

Acceptance Criteria

• We should be able to mock submitted libraries
• The autograder should not require a reference to a submitted library when deserializing
• Mocks should be accurate.