Add support for merchants-of-record

[YodaLightsabr]

https://squareup.com/us/en/the-bottom-line/operating-your-business/merchant-of-record

MoRs (or merchants-of-record) like Square and Toast account for a significant portion of activity on HCB. It would be great to keep track of the merchant IDs for these MoRs, but with our current system, it would replace the memo (which contains information about the real merchant) with the name of the MoR.

Possible solutions:

• Adding a flag for shared_network_id to indicate that the network ID is shared between multiple merchants
• Adding a new field called provider_name to use instead of name when a network ID corresponds to a merchant-of-record

[garyhtou]

This sounds good to me. Let's go with:

Adding merchant_of_record: true to merchants that serve as a Merchant of Record. Within the Ruby gem, when you list of search for a merchant, it should provide this information (e.g. a boolean for whether this merchant is a MoR).

On HCB's end, we'll ignore merchants that are MoR (or add a special case for it).

For now, I'll just be this boolean. In the future, if there's a need, we can add more structured data about the MoR.