Draft: Make IT roles visible in Hotwire

This adds a view to list all IT roles, and also includes it as a subview on the COs View of people.

hr can view the COs View so it was necessary to give them select rights on it.

Although the IT Roles view is auto-updateable as it pulls from just one table, I want to make sure people do not insert or edit certain role types. Current Chemist is maintained by triggers on HR tables so should not be hand edited, and the special role for reconciling reality with the database should not be used by anyone not working on the remote users project. I have therefore provided a trigger function to handle operations on the view so it can throw exceptions if anyone should try to edit those role types.

Closes #18