CDB3-328 CDB3-327 dgf-dutch/english 'prolongation.reason' field should be added when prolongation created, before activation

Summary: prolongation.reason can't be set during prolongation period

X-Request-ID: aea329c8-0749-4f6a-8708-1304aaa91e9a

Actual result: https://prnt.sc/vp74tu

Expected result: reason can be setted with this endpoint