Recognise USDT as a Stablecoin asset

This proposal would recognise USDT as a Stablecoin asset on Osmosis.\n\n\nDetails\n\n Proposal 233 defined Stablecoins as an asset type to used in the incentive category structure. Assets defined as Stablecoins are currently eligible for:\n* Access to the Osmo/Stable Category for their incentivised pools\n* Access to the Stable/Stable Category for their incentivised pools\n* Automatic matching of External incentives within the Stable/Stable Category as per Proposal 377\n\nIn the wider market, USDT is currently the USD Stablecoin with the greatest share of Stablecoin marketcap at ~48% dominance.\n\nOn Osmosis, USDT is currently provided canonically via the Axelar bridge, however, this proposal authorises whichever USDT is authorised as the canonical asset on Osmosis as the stable asset.\n\n\nAbout USDT\n\nLaunched in 2014, Tether was the first stablecoin issued and remains the most prevalent stablecoin in use across the crypto ecosystem.\n\nWebsite: https://tether.to/\n\n\nCommonwealth Thread: https://commonwealth.im/osmosis/discussion/9344-define-new-stablecoin-assets