feat: Multi-variant LocalAsset

[mustermeiszer]

Description

The system already provides a way to amalgamate the same tokens from different chains - e.g., USDC from Ethereum and USDC from Base can be instantly swapped into localUSDC. Issuers can use localUsdc as their pool currency, opening the pool for both variants. We want to extend this behavior. Creating more localXXX versions, allows issuers to accept a more diverse set of tokens - e.g. a localUsdcDai token would allow the use of both Dai and all USDC variants for a pool.

This means that localUsdcDai tokens could be swapped into both Dai and Usdc tokens, while localUsdc tokens could only be swapped into Usdc tokens.

Research/based on

• Needs of issuers to not swap USDC <> DAI or other tokens

How will this affect the code base

• Increase complexity on the pallet-token-mux side due to decimal differences

What are foreseen obstacles or hurdles to overcome?

• Prevent creation of dust due to rounding