Add a new field for storing a submission's internal identification number

Prof. Dăscălescu asked us to add an additional field to the submission creation form, to record the internal tracking number which is already being used by the Bulletin's staff.

This will involve, at the least, the following steps:

Adding a callback to the Schema::get::submission hook, in order to modify the Submission entity's schema. In the callback, we have to add a new property to store the ID in the database (as a non-translatable string).
Modifying the StartSubmission form to add a new field for inputting this property when creating a submission.
Modifying the TitleAbstractForm component to allow displaying / editing this property when editing a publication. Since the Publication entity isn't the same as Submission, we will have to manually load the submission object and the associated ID field from the database.
Add a callback to the Publication::edit hook to allow editing the internal ID through the publication form. Since the internal ID is displayed on the TitleAbstractForm, which is a form connected to the Publication entity, we have to change its edit method to store the value of the internal ID in the associated Submission object.

daria-vcl / BulletinMathematiquePlugin

Add a new field for storing a submission's internal identification number #6