add service provider rewards support

[andymck]

related hip: https://github.com/helium/HIP/blob/main/0087-proportional-service-provider-rewards.md

related proto pr: helium/proto#377

[jeffgrunewald]

If I understand correctly here, the payer that we're using to sum data transfer credits burned by a service provider is the b58 text encoding of the carrier's public key and then we're storing a mapping of that public key to the string-entity key (name) of the service provider stored in the mobile config service but is that mapping not available on-chain such that we can just treat the service provider as a "rewardable entity" and look up their entity key from the metadata database the foundation populates?

[andymck]

If I understand correctly here, the payer that we're using to sum data transfer credits burned by a service provider is the b58 text encoding of the carrier's public key and then we're storing a mapping of that public key to the string-entity key (name) of the service provider stored in the mobile config service but is that mapping not available on-chain such that we can just treat the service provider as a "rewardable entity" and look up their entity key from the metadata database the foundation populates?

good question, my understanding at the time was that we needed to add this to our internally managed DB. I dont recall the exact reason but i think it relates to the fact we only have the payer public key and that is not available as a direct translation on the metadata db populated by foundation ? But i may have just misunderstood and my context of the metadata DB is not that great. @bbalser thoughts?