MM-53924 - Implement push notifications plugin hook and plugin api method (#24350)

* Revert "MM-52804 - Implement SendPushNotification plugin api method (#24273)"

This reverts commit 8418eefb75.

* Revert "MM-53924 - Implement NotificationWillBePushed plugin hook (#24263)"

This reverts commit f13a531bca.

* implement NotificationWillBePushed plugin hook

* implement SendPushNotification plugin api method

* move where we're setting post and channel type

* fix comment

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/plugin/plugintest/api.go

@@ -3639,15 +3639,17 @@ func (_m *API) SendMail(to string, subject string, htmlBody string) *model.AppEr
 	return r0
 }
 
-// SendPluginPushNotification provides a mock function with given fields: notification
-func (_m *API) SendPluginPushNotification(notification *model.PluginPushNotification) error {
-	ret := _m.Called(notification)
+// SendPushNotification provides a mock function with given fields: notification, userID
+func (_m *API) SendPushNotification(notification *model.PushNotification, userID string) *model.AppError {
+	ret := _m.Called(notification, userID)
 
-	var r0 error
-	if rf, ok := ret.Get(0).(func(*model.PluginPushNotification) error); ok {
-		r0 = rf(notification)
+	var r0 *model.AppError
+	if rf, ok := ret.Get(0).(func(*model.PushNotification, string) *model.AppError); ok {
+		r0 = rf(notification, userID)
 	} else {
-		r0 = ret.Error(0)
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(*model.AppError)
+		}
 	}
 
 	return r0