[FIP -200] Add eUSD-FRAXBP Gauge

Proposal to add eUSD/FraxBP to FXS gauge controller

Curve Pool Address: https://curve.fi/#/ethereum/pools/factory-v2-277/deposit

Pool / Token: 0xaeda92e6a3b1028edc139a4ae56ec881f3064d4f

Motivation:
eUSD would be second pool from Reserve that has partnered with Frax using fbp. Aiming to continue.

eUSD is the first RToken deployed on Reserve protocol. It is fully backed by diversified stable assets (currently USDT in Aave and Compound) as well as overcollateralized by staked RSR. During recent USDC depeg it autonomously offloaded depegged USDC collateral and recollateralized with the staked RSR. Staked RSR collects revenue from the underlying collateral and in exchange operates as governance for the RToken.

eUSD can be freely minted or redeemed for the underlying at Register.app.

Voting:
For: Add the eUSD-FRAXBP Gauge
Against: Do nothing

This proposal is up for voting here: Snapshot