Bug 36582: Add option to set library, desk, and register from user menu

Bug 36582: Add option to set library, desk, and register from user menu

This patch adds an expandable "panel" in the user dropdown menu in the
staff client. Expanding the panel will load the form from
set-library.pl, including library, desk and register options if present.

The patch moves the contents of desk_selection.js and
register_selection.js into staff-global.js so that the functionality is
available on every page.

To test, apply the patch and rebuild the staff interface CSS
(https://wiki.koha-community.org/wiki/Working_with_SCSS_in_the_OPAC_and_staff_client).

Test plan stolen from Bug 36572:

1. Have 3 staff accounts to test:
  -STAFF A: superlibrarian
  -STAFF B: loggedinlibrary permission
  -STAFF C: no loggedinlibrary or superlibrarian permission
2. Enable 'UseCirculationDesks' and create some desks. (Admin >
   Circulation desks)
3. Enable 'UseCashRegisters' and create some registers ( Admin > Cash
   registers)
4. Use STAFF A ( superlibrarian ) and make sure you can change branch,
   desk and register.
5. Use STAFF B ( loggedinlibrary permission ) and make sure you can
   change branch, desk and register.
6. Use STAFF C ( no loggedinlibrary or superlibrarian permission ) and
   make sure you can change branch, desk and register.
7. Each time you change you should be redirected to the page you were
   previously on.
8. Turn off UseCirculationDesks, make sure everything still works.
9. Turn off UseCashRegisters, make sure everthing still works.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>