[BE] Handle off chain for Distributors

[thangle-s4v]

Need to figure out how to handle distributors for a campaign:

1. A campaign can have multiple distributors
2. Distributors need to have KYC
3. Distributors need to have ability to do
   3.1 Receive crypto from campaign wallet
   3.2 Convert that crypto amount to be physical money
   3.3 Upload documents, proofs for that campaign

[lamducduong184]

Let me do a research on this issue