Bug 32038: Sidebar and footer style improvements on suggestions page

Bug 32038: Sidebar and footer style improvements on suggestions page

This patch makes some changes to the suggestions template in order to
make the sidebar filter form and bulk action table footer forms more
usable and readable.

Some global changes to <fieldset class="brief"> style are made.

To test, apply the patch and rebuild the staff interface CSS.

- Go to Suggestions.
- Confirm that the sidebar contains two sections: Organize by and Filter
  by.
- Test that the links under "Filter by" work to expand and collapse the
  different sections (bibliographic, suggestion, and acquisition).
- Below the table of existing suggestions you should see the section
  "Change selected suggestions."
- Each form should look good, with labels in bold above each form field,
  with "primary" style submit buttons.
- Because some global styles have been modified, check that fieldsets
  with the class "brief" are still displayed correctly in other areas:
  - In sidebar forms: Patrons, Acquisitions order and invoice searches,
    overdues and holds to pull in Circulation.
  - In other areas: The Quick spine label creator; the upload plugin
    form; the calendar's add holiday form.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>