* Add an option to hide certain users in the UI

* revert changes for admin users routes

* fix sqlstore function name

* Improve slice management

Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

* Hidden users: convert slice to map

* filter with user logins instead of IDs

* put HiddenUsers in Cfg struct

* hide hidden users from dashboards/folders permissions list

* Update conf/defaults.ini

Co-authored-by: Torkel Ödegaard <torkel@grafana.com>

* fix params order

* fix tests

* fix dashboard/folder update with hidden user

* add team tests

* add dashboard and folder permissions tests

* fixes after merge

* fix tests

* API: add test for org users endpoints

* update hidden users management for dashboard / folder permissions

* improve dashboard / folder permissions tests

* fixes after merge

* Guardian: add hidden acl tests

* API: add team members tests

* fix team sql syntax for postgres

* api tests update

* fix linter error

* fix tests errors after merge

Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>
Co-authored-by: Torkel Ödegaard <torkel@grafana.com>
Co-authored-by: Leonard Gram <leo@xlson.com>