Bug 29301: Display error with serials search flatpickr when searching Mana

Bug 29301: Display error with serials search flatpickr when searching Mana

This patch changes the way certain serials search fields are hidden when
a standalone search of Mana is being performed (from the "Search on
Mana" link). Instead of targeting specific labels and inputs to hide we
can hide list items by class.

Unrelated: This patch updates the page heading so that it is different
depending on whether you're searching Koha subscriptions or Mana
subscriptions.

To test, apply the patch and enable Mana.

- Go to Serials -> Advanced search (in the search header).
- The search form should include all fields, including call number,
  vendor, library, location, and "Expires before."
- Click "Search on Mana" in the sidebar.
- This page should have the heading "Mana subscriptions search," and
  there should only be three fields visible: ISSN, Title, and Publisher.
- When you perform a Mana search which returns results the page should
  have the heading "Mana subscriptions (X found).

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>