Predicate support for connecting to Metamask

[luizstacio]

Today the way we build predicates enables users to spend coins from a certain predicate when matching the script requirements. The idea is to have a built-in predicate that enables users to operate with Metamask as a way to sign transactions on Fuel, without the need to have a Fuel Wallet.

The ideal implementation would be a Wallet that uses a Predicate as the underneath signers replacing the need for private keys.

Use case;

• When the application calls the sign method from Predicate Wallet, Predicate will use a MetaMask SDK to request a signature from the user. When it returns, we should treat and add this to the TX and continue the current flow.

[Torres-ssf]

Closing this for now in favor of: #1463
This is already being implemented in https://github.com/FuelLabs/EVM-Wallet-Connector

We need to decide if this could be a wallet connector that we would have in the SDK, after #1463, or if we are going to add some docs on the SDK to explain the version that is being done here

[danielbate]

Agreed this should be done via the wallet connector with examples / documentation