Build core FungibleTokenSwitchboard features

[alilloig]

Issue To Be Solved

Build the core features specified in the epic. Also build the tests for the features

Suggest A Solution

• We will write a new contract “FungibleTokenSwitchboard” that will feature a resource “Switchboard” conforming to {FungibleToken.Receiver} but instead of storing a vault balance, it will store a record of these capabilities: Capability<&AnyResource{FungibleToken.Receiver}>.

• The deposit function enforced by the {FungibleToken.Receiver} will then check the type of the @FungibleToken.Vault received as an argument and route it to the proper Capability<&AnyResource{FungibleToken.Receiver}>. If there is no capability matching the deposited FT, the transaction will fail.

• The owner of the Switchboard resource will be able to call the function addVaultCapability(switch: Capability<&{FungibleToken.Receiver}> in order to store a new one of these capabilities.

• The Switchboard resource also should expose a getVaultCapabilities(): [Capability<&{FungibleToken.Receiver}>] in order to allow buyers to know if the token they are willing to use for the payment is supported by the seller / payment receiver.