Bug 9422: Don't allow access to 'Upload patron images' when patronimages syspref...

Bug 9422: Don't allow access to 'Upload patron images' when patronimages syspref is off

In addition to checking the patron image upload permission, this
adds a check for the patronimages system preference to the tools
home page and sidebar.

To test:
- Check that the patron image upload tool only displays when
  - system preference patronimages is set to 'Allow'
    and user is either
  - superlibrarian or
  - has bath_upload_patron_images permission
- Save URL of patron image uploader page
- Turn off patronimages
- Verify you get redirected to the home page of Koha when trying
  to access the page

Note: this redirect is already used by the stock rotation feature.
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>