Prop 450: Signalling Proposal for OSMO/USDT incentives

This is a signalling proposal to include the USDT pool OSMO/USDT (#831) into the set of assets that receive OSMO liquidity incentives. After this proposal has passed governance, pool #831 will be added to the regular incentives program of Osmosis.

## About USDT
Launched in 2014, Tether was the first stablecoin issued and remains the most prevalent stablecoin in use across the crypto ecosystem.

Website: https://tether.to/

Commonwealth Thread: https://commonwealth.im/osmosis/discussion/10231-osmousdt-incentives