assets/admin/origin-save: Enable to add note when rejecting a request

In the save code now administation page, display a new modal when
rejecting a save request enabling to add a rejection note through
the use of a text area.

Default behavior is to enter a custom note but a couple of prefilled
rejection notes can be selected for the following cases:

  - the origin URL is not a repository link
  - the visit type for the origin URL is not valid
  - the origin URL cannot be found

Related to T3256
Related to T3257