TIP-111: Increase FEI Stable backing to 90-100%

This on-chain proposal will perform the following actions :

• Migrate stETH (Lido staked ETH) to a PCVDeposit where the Chainlink oracle is used to check for slippage, instead of a hardcoded 1:1 peg (the parameter for slippage check keeps the same behavior, but will tolerate a slippage vs the Chainlink oracle price, and not vs a theorhetical 1:1 peg).
• Unstake all B-70WETH-30FEI from Balancer gauge, remove FEI/WETH liquidity from Balancer, burn the FEI, and move WETH to PSM

These actions are part of TIP-111 and will allow Guardian to perform actions to defend the FEI peg and continue to increase the stable backing (percentage of stable assets in the PCV).

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Also contains code from FIP_104b: Withdraw all liquidity from the DPI LBP.

This FIP cleans up and finishes elements of the PCV reinforcement process snapshotted here: https://snapshot.fei.money/#/proposal/0x2fd5bdda0067098f6c0520fe309dfe90ca403758f0ce98c1854a00bf38999674
and discussed here: https://tribe.fei.money/t/fip-104-fei-pcv-reinforcement-proposal/4162 .

Specifically it:

• Exits the LBP pool and withdraws all liquidity to the compound DAI deposit
• Withdraws the DPI from the deposit to the TribalCouncil multisig, using the ratioPCVController
• Deposits the DAI on the deposit into Compound