Bug 14697: Make controller methods rely on the stashed user

Bug 14697: Make controller methods rely on the stashed user

This patch adjusts the return values and HTTP status codes, as well as
removing the use of C4::Context->userenv. It also makes the date
calculation happen on the DB engine in the case of resolving the claim.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Lisette Scheer <lisetteslatah@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>