Bug 29825: Preview of authority record on edit mode as MARC formatted view

Bug 29825: Preview of authority record on edit mode as MARC formatted view

This bug adds a new functionality on Edit mode of a new or existing authority.
Add a new button 'MARC Preview' in order librarian have the ability to preview
the record on MARC plain structure mode and have all fields and subfields
that entered before save/update the record.

To test:
1. Open or add an authority
2. The preview button isn't on toolbar
3. Apply the patch
4. Do step 1
5. The preview button exists
6. Do some changes or not to the authority record
7. Click to Preview MARC button and a modal window will appear with all fields
   indicators and subfields that filled in the form of cataloguing.

Mentored by: Andreas Roussos

Signed-off-by: Phil Ringnalda <phil@chetcolibrary.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>