Gasless Enhancement: Enable custom messages inside the signature request pop-up

[sauravtom]

The Gasless SDK allows anyone to enable gasless transactions in their dApp.
Gasless Docs: https://docs.biconomy.io/products/enable-gasless-transactions

We want to enable the auto signature modification functionality in the gasless SDK to allow the dApp to show a custom message in the wallet pop-up.

For instance, the message could read "Gasless Transactions for : Powered by Biconomy"

Resources:
https://docs.metamask.io/guide/signing-data.html#signing-data-with-metamask
https://medium.com/metamask/eip712-is-coming-what-to-expect-and-how-to-use-it-bb92fd1a7a26
https://hackernoon.com/a-closer-look-at-ethereum-signatures-5784c14abecc