Feat: Wallet CLI - command to authorise signers

[hopeyen]

Problem statement

Data Consumers, as they will handle their own receipts, must be able to authorise signers for the receipts, who will be responsible sending signed receipts for the sender of the escrow account. The sender and signer must be different by the constraint of Escrow contract.

Expectation proposal

Provide an easy CLI command to authorise a signer.
Similar to all other wallet commands, inputs include eth provider, network subgraph, sender private key.
In addition, to set an authorised signer, take an additional param for the signer address.