Add withdraw function to liquidity pools

What is being proposed: Relaunch the wbtc/lfbtc and eth/lfeth pools, provide a Withdraw function that allows for immediate collection of LIFT earned.

Why are we doing this: Easier to for our protocol to be consumed by Zapper/Harvest/Pickle and others.

Details of the change: Provide a withdraw function to the LP contract that redeems earned rewards immediately. A variable will be provided to determine the multiplier (bonus rewards) someone earns if they choose to stakeInBoardroom instead. Adjustment of the variable will be based on DAO vote.

Impact for the stakers: Everyone will have to migrate liquidity to the new contract upon launch. Previous contract will be disabled and LIFT burned, any unstaked LIFT prior to burn and disable will be forever lost.

IMPORTANT: LIFT earned in wbtc/lfbtc and eth/lfeth liquidity pools MUST be redeemed (stakedInBoardroom) by 7/11/2021 1pm EST. After this moment it will be impossible to claim earned LIFT from these pools as all LIFT will be burned from pools.