Prop 726: Add DYM to Transaction Fee Whitelist

This proposal adds DYM to the list of fee tokens able to be used on Osmosis.

This allows users whose only interaction with the Cosmos ecosystem is via Dymension to be able to transact for the first time on Osmosis.

## About Dymension
Dymension is a decentralized Delegated Proof-of-Stake L1 blockchain secured by the DYM token. It is custom built to provide RollApps with security, interoperability, and liquidity.

Dymension is akin to an internet service provider. It serves as a decentralized router that connects RollApps to the crypto economy. Dymension facilitates the vertical integration of modular blockchains in which network and liquidity bootstrapping is coupled in one user experience reducing the amount of time to deploy a blockchain to as little as a few minutes.

Forum Thread: https://forum.osmosis.zone/t/add-dym-to-transaction-fee-whitelist/2391