[API] Add notification endpoint (#9488)
* [API] Add notification endpoints
* add func GetNotifications(opts FindNotificationOptions)
* add func (n *Notification) APIFormat()
* add func (nl NotificationList) APIFormat()
* add func (n *Notification) APIURL()
* add func (nl NotificationList) APIFormat()
* add LoadAttributes functions (loadRepo, loadIssue, loadComment, loadUser)
* add func (c *Comment) APIURL()
* add func (issue *Issue) GetLastComment()
* add endpoint GET /notifications
* add endpoint PUT /notifications
* add endpoint GET /repos/{owner}/{repo}/notifications
* add endpoint PUT /repos/{owner}/{repo}/notifications
* add endpoint GET /notifications/threads/{id}
* add endpoint PATCH /notifications/threads/{id}
* Add TEST
* code format
* code format
6543