Governance Frtamework for Portals

[ARC] - Portals governance framework Portals is a powerful Aave V3 feature allowing to supercharge cross-chain bridges liquidity.

Portals have been presented in this governance thread: https://governance.aave.com/t/portals-powering-the-multi-blockchain-multiverse/6889 22

This proposal intent to create a standard framework for entities willing to be whitelisted by Aave V3 to be a standard-compliant candidates.

This framework will allow entities to request Credit lines to the Aave V3 protocol on multiples networks to increase their liquidity efficiency while increasing protocol revenue by fee collection.