[PIP-021] Add Curve and Convex Receivers for PayPool/mkUSD pool to receive PRISMA rewards

This proposal aims to add receivers for the PayPool/mkUSD metapool on both Curve and Convex. It will allow vePRISMA voters to direct PRISMA emissions to the pool once it is passes as a gauge and further grow TVL and liquidity for mkUSD. To drive this process, Trident will incentivize the PayPool/mkUSD metapool.

Read More: https://gov.prismafinance.com/t/pip-021-add-curve-and-convex-receivers-for-paypool-mkusd-pool-to-receive-prisma-rewards/127