FIP-53: Farm d3pool on Convex

Summary

This proposal mints 50M FEI to deposit in the Curve d3pool (FRAX, FEI, alUSD), and stake the LP tokens on Convex to earn CRV & CVX rewards (currently ~25% APR).

Motivation / Background

See the post "FIP-53: Enter the Curve Wars" on the forum for full context : https://tribe.fei.money/t/fip-53-enter-the-curve-wars/3715

This proposal would be the first integration of Fei Protocol with the Curve / Convex ecosystems, and would be our first step in farming CRV and CVX tokens.

This would also increase the liquidity of FEI against other decentralized stablecoins such as FRAX and alUSD.

Specification

We can execute everything in one transaction, directly in the proposal. The DAO Timelock will mint itself 50M FEI, deposit in the d3pool, and then stake the LP tokens on Convex.