SYS-4189 multi currency support

[nahuseyoum]

Proposed changes

This PR enables support for multi currency payment when sending transactions via the Gateway. This means users will be able to pay Relayers in a variety of ERC20 tokens.

Tests and Benchmarks are also updated to be compatible.

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[thadouk]

Overall nice work. Is it possible to avoid the hardcoding of mnemonics and the dependency between accounts and genesis.

[thadouk]

can this be abused? meaning any ERC20 token can be used as a payment proof?

[nahuseyoum]

This is a good question. If someone sends a transaction direct to chain, and decides to pay for it, it will be done voluntarily (the whole payment_info is optional). The real check to make sure supported tokens are used as payment is done in the gateway by the relayer.