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/channels/app/plugin_api.go

@@ -1267,30 +1267,7 @@ func (api *PluginAPI) GetUploadSession(uploadID string) (*model.UploadSession, e
 	return fi, nil
 }
 
-func (api *PluginAPI) SendPluginPushNotification(notification *model.PluginPushNotification) error {
-	var profiles map[string]*model.User
-	var err error
-	if notification.Channel.Type == model.ChannelTypeGroup {
-		if profiles, err = api.app.Srv().Store().User().GetAllProfilesInChannel(api.ctx.Context(), notification.Channel.Id, true); err != nil {
-			return err
-		}
-	}
-
-	sender, appErr := api.app.GetUser(notification.Post.UserId)
-	if appErr != nil {
-		return appErr
-	}
-	user, appErr := api.app.GetUser(notification.UserID)
-	if appErr != nil {
-		return appErr
-	}
-
-	postNotification := &PostNotification{
-		Post:       notification.Post,
-		Channel:    notification.Channel,
-		ProfileMap: profiles,
-		Sender:     sender,
-	}
-	api.app.sendPushNotification(postNotification, user, notification.ExplicitMention, notification.ChannelWideMention, notification.ReplyToThreadType)
-	return nil
+func (api *PluginAPI) SendPushNotification(notification *model.PushNotification, userID string) *model.AppError {
+	// Ignoring skipSessionId because it's only used internally to clear push notifications
+	return api.app.sendPushNotificationToAllSessions(notification, userID, "")
 }