Allow API to assign new user to a specific organization (#21775)

* Allow API to assign new user to a specific organization

* Add defer block to test

* Add API tests and return 400 instead of 500 for bad orgId

* Minor test improvements

pkg/api/admin_users.go

@@ -14,6 +14,7 @@ func AdminCreateUser(c *models.ReqContext, form dtos.AdminCreateUserForm) {
 		Email:    form.Email,
 		Password: form.Password,
 		Name:     form.Name,
+		OrgId:    form.OrgId,
 	}
 
 	if len(cmd.Login) == 0 {
@@ -30,6 +31,11 @@ func AdminCreateUser(c *models.ReqContext, form dtos.AdminCreateUserForm) {
 	}
 
 	if err := bus.Dispatch(&cmd); err != nil {
+		if err == models.ErrOrgNotFound {
+			c.JsonApiErr(400, models.ErrOrgNotFound.Error(), nil)
+			return
+		}
+
 		c.JsonApiErr(500, "failed to create user", err)
 		return
 	}