Bug 33902: Move modal inside HTML body

Bug 33902: Move modal inside HTML body

To test:
-Go Administration > Libraries and add a URL for a branch.
-Also add some OPAC info: ( via HTML Customizations )
-Now find a record belonging to that branch and bring up the OPAC detail page.
-In the holdings table there should be a link under the 'Current library' column.
-Clicking it should bring up a modal.
-Make sure the modal pops up correctly, can be dismissed, and the 'Visit web site' link works.

Nothing about the appearance or behavior of the page should change.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit e1be2791b807948c85ae48e471594a7c68709e84)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>