Bug 20651: Improve full supplier metadata display

Bug 20651: Improve full supplier metadata display

This patch improves the display of the extra metadata that may be
returned by an ILL supplier.

The display of the metadata has been moved from the "Toggle full
supplier metadata" link at the bottom of the page to a button on the
right of the request toolbar, labelled "Display supplier metadata".
Clicking this button opens a modal displaying the metadata.

To test:
1) Ensure ILL is enabled and you have at least one request
2) From the "View ILL requests" page, click "Manage request" on a
request
3) Click the "Display supplier metadata" button on the right of the
toolbar
4) Observe that a modal opens containing the metadata

Signed-off-by: Magnus Enger <magnus@enger.priv.no>
The modal looks good!

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>