Add CS API device tests (#3029)

Adds tests for
- `/devices`
- `/delete_devices` (also adds UIA)

userapi/api/api.go

@@ -224,7 +224,6 @@ type PerformDeviceUpdateRequest struct {
 }
 type PerformDeviceUpdateResponse struct {
 	DeviceExists bool
-	Forbidden    bool
 }
 
 type PerformDeviceDeletionRequest struct {

userapi/internal/user_api.go

@@ -386,11 +386,6 @@ func (a *UserInternalAPI) PerformDeviceUpdate(ctx context.Context, req *api.Perf
 	}
 	res.DeviceExists = true
 
-	if dev.UserID != req.RequestingUserID {
-		res.Forbidden = true
-		return nil
-	}
-
 	err = a.DB.UpdateDevice(ctx, localpart, domain, req.DeviceID, req.DisplayName)
 	if err != nil {
 		util.GetLogger(ctx).WithError(err).Error("deviceDB.UpdateDevice failed")