Bug 21699: Allow circulation messages to be editable

Bug 21699: Allow circulation messages to be editable

During a Webinar discussion regarding the new placement of the circulation messages appearing in the Patron Detail page.  It was commented by a librarian that it would be nice to have the circulation messages editable. At times libraries need to keep a specific message on a patrons account with the details such as what branch it was written from and the staff member that wrote it, but it would be nice to be able to edit this message.

Test Plan:
1) Apply this patch
2) Restart all the things!
3) Browser to a patron record
4) Create a new patron message
5) Note the patron message now has an "edit" button
6) Edit the existing message using the edit button and form
7) Check the action logs for that message, note there is a modification
   logged to that message if BorrowersLog is enabled

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Laura Escamilla <laura.escamilla@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>