Bug 35511: Add visual indicators of patron edit form collapsible sections

Bug 35511: Add visual indicators of patron edit form collapsible sections

This patch updates CSS and markup in the patron add/edit form so that
there is better visual indication that sections can be collapsed by
clicking headings.

The JS function for showing and hiding sections has also been updated to
reduce verbosity.

Unrelated markup change for the sake of accessibility: A <label> has
been added to the "Show collapsed fields" checkbox which is seen when
CollapseFieldsPatronAddForm is active.

To test, apply the patch and go to Patrons -> New patron.

- Each section of the form should have an arrow indicator by the section
  heading indicating whether it is expanded or collapsed.
- Mousing over the heading should show a border to help show the
  clickable region.
- Clicking the header should collapse the section and the arrow
  indicator should change to reflect that the section is collapsed.
- Go to Administration -> Sytem preferences and search for
  CollapseFieldsPatronAddForm.
- Make some selections from the dropdown and save your changes.
- Return to the patron entry form and confirm that your selections are
  collapsed by default.

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>