Bug 22121: Display 'Price paid' on ILL requests according to CurrencyFormat pref

Bug 22121: Display 'Price paid' on ILL requests according to CurrencyFormat pref

To test:
- Install BLDSS backend
  see: https://wiki.koha-community.org/wiki/ILL_backends
- Add a new BLDSS ILL request
- Edit ILL request
- Fill in Price paid field
- Verify Price paid is formatted correctly on 'Manage ILL request'
  page

Signed-off-by: Ethan Amohia <ethan.amohia@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>