Adds an endpoint where scripts and unit test values can be submitted to to verify that a criteria script is valid. This helps prevent crashing assignments at a very early stage. The values are stored inside the assignment, so later edits that would invalidate these tests can be detected too.
Also links metric instance types to metric names so they can be type-checked and the system can generate suitable template scripts and unit tests for assignments.
Requires UI updates to be functional.
Resolves #100 (closed)
To be filled in by the reviewers