Research and integrate flexible gas fees in any asset via DEX Pallet

[RyanDinh8]

Is your feature request related to a problem? Please describe.

• DEX Pallet repo: Asset Conversion pallet paritytech/substrate#12984 => Currently archived
• New DEX Pallet repo: https://github.com/paritytech/polkadot-sdk/tree/master/substrate/frame/asset-conversion
• Example of flexible gas fees in any asset via DEX Pallet: https://github.com/bee344/subxt/blob/dcae1aa747502dcd0e6e4c51d67575c5342a94ef/subxt/examples/asset_hub_westend.rs#L460