[PRISMA] [PIP-003] Add Convex PRISMA-ETH Pool so it can receive PRISMA rewards

Quorum: 7.63m CVX

This proposal is straightforward and simply proposes to add support PRISMA/ETH as a receivers so that lockers may vote to direct emissions to it.

Read more: https://gov.prismafinance.com/t/rfc-add-convex-prisma-eth-pool-so-it-can-receive-prisma-rewards/51