Filterconfig association table

Description

Closes issues: Related issues: LA-1397

Add an association table between filterconfig and usergroup, to allow a row in the filterconfig table to be associated with multiple usergroups. Also added a third usergroup to verify that this is the case.

I've manually verified that the migration script works by working on a database in dev, before doing the last two migrations from this branch.

Notes to reviewer

[Are there points in the code the reviewer needs to double check or where you would like advice?]

Type of change

• New feature
• Breaking change
• Bug fix
• Improvement

Tests

General

• Tests have been added that prove my fix is effective or that my feature works
• Related tests have been modified/removed

Hypothesis testing:

• Soak testing has been done
• Distribution between positive / negative cases has been checked

Database

• Includes changes to database schema
• Includes necessary database migrations

Configuration

• Includes changes to configuration
• Includes configuration migration instructions in documentation

General

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My branch has recently been updated with new changes in dev before this merge request
• I have made corresponding changes to the documentation