[BIP-495] Enable frxETH/sfrxETH metastable pool gauge [Optimism]

PR with Payload

https://github.com/BalancerMaxis/multisig-ops/pull/666

Summary:

We request adding frxETH/sfrxETH metastable pool on optimism to BAL gauge

References/Useful links:

Link to • Website • Documentation • Github Page

Protocol Description:

frxETH is Frax's wrapped ETH token and sfrxETH is its staked interest bearing version

Motivation:

As a joint effort with FRAX and Beethoven X, we aim to increase liquidity of FRAX, sFRAX, frxETH, sfrxETH, to make Balancer a liquidity hub for frax assets on optimism. The BAL gauge will facilitate the process.

Specifications:

1. Governance: FRAX governance process can be seen here and their snapshot here.
2. Oracles: Rate provider contract for sfrxETH, the pool does not rely on additional oracles.
3. Audits: See here
4. Centralization vectors: see here.
5. Market History: See here
6. Value: Balancer will earn the protocol fee on interest bearing sfrxETH in the pool and so will LPs. The BIP-19 flywheel will incentivize TVL to grow here with trading volume and our staked ethereum pillars will continue to have Balancer as their ideal liquidity destination.

Link to pool: https://op.beets.fi/pool/0xa71021492a3966eec735ed1b505afa097c7cfe6f00000000000000000000010d Link to child gauge: https://optimistic.etherscan.io/address/0xc46AB6Aa92F7c30B8Fb1D445b4B957203EbBbd6e Root gauge: https://etherscan.io/address/0x5622821A3b993f062Ff691478Bbb7d551c167321#code

Specification:

The Balancer Maxi LM Multisig eth:0xc38c5f97B34E175FFd35407fc91a937300E33860 will interact with the GaugeAdderv4 at 0x5DbAd78818D4c8958EfF2d5b95b28385A22113Cd and call the addGauge function with the following arguments: gauge(address):0x5622821A3b993f062Ff691478Bbb7d551c167321 gaugeType(string): Optimism

Additionally, this pool is requesting core pool status as per BIP-457