feat: ERC20TransferableReceivable contract gas optimizations

[mliu]

This pull request aims to cut gas costs on the ERC20TransferableReceivable contract. The changes proposed are based on the findings of a gas profiler and include the following optimizations:

• Remove the ERC721Enumerable functionality since it is not critical to the final product. Request Finance already knows all of a user's invoices and can map each one to their respective receivables. Previously we only used this to power our demo experience on the Huma dApp.
• Stop using ERC721URIStorage as a glorified storage field for requestID. This is a significant waste of gas since strings need to be processed and stored. Instead, revert to the base ERC721 URI storage and create a new field requestID in the ReceivableInfo struct.
  • This still allows for us to upgrade the receivables contract with metadata hosted on a storage service like IPFS.
  • Instead of storing a base64 encoded string of the serialized request ID in the tokenURI, we store a bytes32 hash of the deserialized request ID (

    requestNetwork/packages/multi-format/src/hexadecimal-serializable-multi-format.ts

    Line 59 in 2b03cd1

    value: `0x${this.removePrefix(formatted.toLowerCase())}`,

    for more context)

Using hardhat-gas-reporter, I measured a decrease in mint call costs from 320k to 177k. These changes cut gas costs per mint by almost half, resulting in savings of approximately $8-10 per mint on mainnet with current gas prices.

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