[BIP-71] Enable wstETH/weth Gauge [Arbitrum]

Summary:

This pool uses the new composable stable pool factory which allows us to apply the protocol fee to yield bearing tokens. This gauge would enter as a "core pool" under BIP-19, meaning protocol fees earned by this pool would be used to bribe for votes on it. Since all fees collected on Arbitrum are distributed through bribes, this pool will also receive bribes from those fees in proportion to this pool's TVL relative to other Arbitrum core pool TVL.

References/Useful links:

Link to: • Website • Documentation • Github Page
• Communities • Other useful links?

Protocol Description:

wstETH is liquid staked ETH. WETH is wrapped Ether.

Motivation:

One of Balancer's near term strategic objectives is to attract more yield bearing liquidity. The launch of wstETH on Arbitrum presents a huge opportunity to make Balancer the main liquidity destination for wstETH. Adding this wstETH/weth pool will allow the rest of our wstETH liquidity to interact and arbitrage with other weth liquidity on Arbitrum. The goal moving forward is center most of Balancer's liquidity around wstETH and other yield bearing tokens, so "connecting" pools like this one are necessary to ensure trades can be routed effectively.

Specifications:

1. Governance: Find more information about governance on Lido's forum.

2. Oracles: This pool relies on a rate provider for wstETH which the Orb Collective integrations team graciously deployed. See here.

3. Audits: See here.

4. Centralization vectors: See here for information on this.

5. Market History: See here.

6. Value: Balancer will earn the protocol fee on wstETH yield. We'll migrate this pool to wstETH/bbaWETH as soon as that's feasible. In the interim we need to position Balancer as the primary liquidity destination for wstETH so while this pool isn't the ideal configuration, it's better than being on the sidelines for weeks/months as wstETH liquidity goes to other exchanges.

Link to pool Link to gauge: 0x6f825C8bbf67eBb6bc35cf2071daCD2864C3258E