XYZ-37: Advanced Permissions Phase 1 Backend. (#8159)

* XYZ-13: Update Permission and Role structs to new design.

* XYZ-10: Role store.

* XYZ-9/XYZ-44: Roles API endpoints and WebSocket message.

* XYZ-8: Switch server permissions checks to store backed roles.

* XYZ-58: Proper validation of roles where required.

* XYZ-11/XYZ-55: Migration to store backed roles from policy config.

* XYZ-37: Update unit tests to work with database roles.

* XYZ-56: Remove the "guest" role.

* Changes to SetDefaultRolesFromConfig.

* Short-circuit the store if nothing has changed.

* Address first round of review comments.

* Address second round of review comments.

model/user_test.go

@@ -263,11 +263,11 @@ func TestCleanUsername(t *testing.T) {
 
 func TestRoles(t *testing.T) {
 
-	if IsValidUserRoles("admin") {
+	if !IsValidUserRoles("team_user") {
 		t.Fatal()
 	}
 
-	if IsValidUserRoles("junk") {
+	if IsValidUserRoles("system_admin") {
 		t.Fatal()
 	}