Implement endpoints needed for Permissions revamp

[pavish]

- [ ] database_setup.add_from_known_connection
- [ ] database_setup.add_from_scratch
- [ ] databases.list
- [ ] databases.get
- [ ] databases.delete
- [ ] databases.collaborators.list
- [ ] databases.collaborators.add
- [ ] databases.collaborators.delete
- [ ] databases.collaborators.patch (only allow patching role, not user)
- [ ] databases.pg.drop
- [ ] databases.pg.privileges.list
- [ ] databases.pg.privileges.grant
- [ ] databases.pg.privileges.revoke
- [ ] databases.pg.privileges.transfer_ownership
- [ ] databases.pg.privileges.list_owned_objects_recursively
- [ ] databases.pg.privileges.transfer_ownership_recursively
- [ ] database_servers.get
- [ ] database_servers.login_roles.list
- [ ] database_servers.login_roles.store_password
- [ ] database_servers.login_roles.remove_stored_password
- [ ] database_servers.login_roles.pg.add
- [ ] database_servers.login_roles.pg.delete
- [ ] database_servers.databases.list
- [ ] groups.list
- [ ] groups.get
- [ ] groups.add
- [ ] groups.delete
- [ ] groups.members.list
- [ ] groups.members.get
- [ ] groups.members.add
- [ ] groups.members.delete
- [ ] groups.members.patch
- [ ] schemas.list: should include privilege information for all roles
- [ ] schemas.add: should require owning role
- [ ] schemas.get: should include privilege information for all roles
- [ ] schemas.privileges.grant
- [ ] schemas.privileges.revoke
- [ ] schemas.privileges.transfer_ownership
- [ ] schemas.privileges.list_owned_objects_recursively
- [ ] schemas.privileges.transfer_ownership_recursively
- [ ] tables.list: should include privilege information for all roles
- [ ] tables.add: should require owning role
- [ ] tables.get: should include privilege information for all roles
- [ ] schemas.privileges.grant
- [ ] schemas.privileges.revoke
- [ ] schemas.privileges.transfer_ownership
- [ ] Add accent colors and avatar initials to users

[pavish]

Related document: https://hackmd.io/@mathesar/rkjSF5IUC