Bug 28694: Check alert in cataloguing should be a static message

Bug 28694: Check alert in cataloguing should be a static message

This patch modifies the basic cataloging interface so that form
validation errors are collected in a static "dialog" at the top of the
page instead of showing in a transient JavaScript alert.

The text of the message is roughly the same as it was in the alert, and
links have been added so that the user can click to jump directly to the
field referenced.

If the user scrolls down away from the static error message, a button
appears in the floating toolbar to jump back to the message.

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).

- Go to Cataloging and create a new record using the basic cataloging
  editor and a framework which has multiple mandatory fields defined
  (e.g. an unmodified default framework)
- Without entering anything in mandatory fields, click the "Save"
  button.
- You should see a message box appear at the top of the page.
  - It should list each missing mandatory subfield and tag, each with a
    "Go to field" link next to it.
  - Clicking the "Go to field" link should switch you to the correct tab
    and scroll the mandatory field into view.
- When you have scrolled down far enough for the error messages to be
  offscreen, an "Errors" button should appear in the floating toolbar.
  Clicking it should scroll the box back into view.
- The JS function for scrolling to a particular element on the screen
  has been modified, so test that the links in the toolbar for
  individual tags still work correctly.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>