This PR cleans up the code to be more extensible in supporting more chains in the future.
Supports using existing mappings in the original L1 list as the source of truth, using those values over any fetched ones for a given token. This allows manual entry/overrides of any mappings, even those on chains where fetching is not directly supported in this library (ex. Celo).
Uses different public optimism RPC endpoint (ankr). previous one seemed to get rate limited often, resulting in missing mappings.
Adds auto-formatting from prettier library.
Tested by comparing output of this updated library with previous one and seeing no difference. Then adding some manual mappings to the input L1 list and seeing the correct additions to the output.
Tested by comparing output of this updated library with previous one and seeing no difference. Then adding some manual mappings to the input L1 list and seeing the correct additions to the output.