Bug 28588: (follow-up) Make the API use the new method

Bug 28588: (follow-up) Make the API use the new method

This patch adapts the controller method for resolving a return claim so
it uses the Koha::Checkouts::ReturnClaim method instead.

To test:
1. Run:
   $ kshell
  k$ prove t/db_dependent/api/v1/return_claims.t
=> SUCCESS: Tests pass!
2. Apply this patch
3. Repeat 1
=> SUCCESS: Tests pass!
4. Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>