Support for Kit definition on diaperbase and kit requests on partnerbase

[SarahAdelaide]

Diaper banks would like to allow partners to request event-specific kits. For example: first time menstrual kits, new infant kits, first time adult incontinence kits. A first-time menstrual kit might contain single pads of several sizes as well as tampons of several sizes.

once a kit/bundle is defined on diaperbase (rubyforgood/human-essentials#1846), that kit should be populated on the associated partnerbase instances as a requestable product.

Kits are composed of a pre-defined collection of existing products offered by the diaperbank.
Diaperbank users should be able to define
-kit name
-what products are in the kit
-how many of each product are in the kit
-maximum number of a given kit partners can order at one time