Bug 32788: Order curbside pickup slots chronologically

Bug 32788: Order curbside pickup slots chronologically

We need to order the slots chronologically, not depending on when they
have been added.

Test plan:
Create a slot 13 to 17 the another one 8 to 12
We want to display 8 to 12 before 13 to 17.
Confirm that this patch fixes that on the 3 following views:
Curbside pickups admin
Curbside pickups staff side
Curbside pickups at the OPAC

Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>