[Feature]: Create the option to set taker-fee for single direction pairings (not bi-directional)

[LeonoorsCryptoman]

Summary

Add the option to set the taker-fee for specific traderoutes. This enables diversification for the Taker Fee DAO to set the fee for directional trades.

Problem Definition

In the current setup of the taker fee it can only be set for a pairing (e.g. ETH <> USDT). This means that it doesn't matter whether the user traders from ETH > USDT or from USDT to ETH. The taker fee is the same for both directions of the trade.

An interesting opportunity can arise when the taker fee can be set for each direction separately, such that for example USDT > ETH is subjected to a 0% taker fee and ETH > USDT is subjected to a 0.02% taker fee. This will allow diversification on setting the taker fees, but also to make some specific trade routes more advantageous.

For example; USDC.axl/USDC is being rebalanced on a regular basis because the canonical version of USDC is more popular. The taker fee to go from USDC > USDC.axl could be set to 0% to make this more attractive to use as a traderoute, and thereby causing a more automated rebalancing through arbitrage opportunities.

Proposed Feature

Create the option to not only set the taker fee on a denom-pairing, but also in which direction. For example the ability to set a taker fee for denom0 > denom1 and a taker fee for denom1 > denom0