Create function to update metadata in FT contracts

[mfornet]

After ERC20 tokens are bridged to NEAR as NEP141 the metadata needs to be updated. This is also the case when tokens are deployed as ERC20 inside Aurora. This issue tracks the implementation of helper functions to do this safely using a library.

The issue is opened in this library, since the logic for this should be implemented in this repository, and then we should be using it from CLI tool and frontend.

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Tasks involved:

• Pull metadata from ERC20 contracts in Ethereum.
• Push metadata to NEP-141 in NEAR. Use this function to update NEP141 metadata
• Push metadata to ERC-20 contracts inside Aurora. Use AdminControlled interface for updating storage inside contracts.

Notice that for pushing information, they can only be done with from some particular accounts (owner accounts). It would be useful to throw a meaningful error in case the account used is not the expected one.

[mfornet]

@paouvrard it would be useful to have your input, on where this functions should live.

[paouvrard]

@mfornet
Tasks 1 and 2 (pulling metadata from ERC-20 and updating NEP-141) could go in nep141-erc20 and task 3 (pushing metadata to Aurora) could go in aurora-erc20. But we can also make a metadata package or add it to utils if we don't want them to be separated.
If we plan to make a connector to trustlessly bridge metadata, then I think having a metadata connector package in the client libs makes sense.

[0x3bfc]

If we plan to make a connector to trustlessly bridge metadata, then I think having a metadata connector package in the client libs makes sense.

I'd say if we will have this especially for only bridging the ERC-20 metadata, then It should go to nep141-erc20 and aurora-erc20 but if it will be more generic for bridging any contract's metadata to aurora, then it should be in a separate package.