[VPS-176] Roles can be managed via the Manage Groups table

[JordanBlenn]

Description:

AS A: scenario creator
I WANT: to be able to alter the roles for my scenario
SO THAT: if I make a typo with one of my roles, I can rename it without any issues

AC's:

1. A "Manage Roles" button is added to the header bar of the Manage Groups page
2. When clicked, it pulls up a list of roles, with the opportunity to add or remove roles as necessary.
3. If a role is added:

• this role is added to the database for this scenario

4. When a CSV file is uploaded, the role headings must be the same as the roles created by "Manage Roles" or the file is rejected (stops overwriting previous Roles with new ones and fucking stuff up around role permissions).

Technical Discussion:

• see comment on [VPS-154](2)(0.5) Uploading a CSV file creates appropriate groups and assigns roles (No UI) #154 for extra info around this
• adding and removing roles when CSV data is in there is OOS (future stories)