Bug 36641: Add endpoint for fetching circulation rules

Bug 36641: Add endpoint for fetching circulation rules

This patch adds an endpoint for fetching ciruclations rules given the
constraints of the passed parameters.

We optionally expect item_type, library and patron_category as query
parameters and we return a list of relevant circulation rules pertaining
to that combination of requirements.

You can also add a list of `rules` as a query parameter to limit the
response to only the rules you are interested in for this combination.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>