ARC: Add UST as a borrowable asset

Adding UST as a borrowable asset seems like a no-brainer to me.

The support of more decentralized stables is a need shared across the larger DeFi ecosystem. By adding UST support for borrowing on Aave, the protocol can cement itself as a luminary and full-suite of assets.

I would note that the market cap of UST has 10x since the original time of posting:

In addition, there are robust (and frequent) liquidity mining proposals in the Terra ecosystem aimed at expanding UST across networks and chains. UST can now be found on Solana, BSC, Polygon, Ethereum, and soon Avalanche, driving the demand for borrowing.

Would this New Asset listing be supported in Aave V3? Or only V2?