Add ERC20 token support

[0a1c]

Add capability to:

• Add/manage ERC-20 tokens
• Fetch user balances
• Show hard-coded ERC-20 currencies

Details

This PR builds infrastructure for ERC-20 tokens, similar to CW20 tokens, with a few distinctions. ERC20 queries differ from CW20 and Secret queries in that they query a JSON-RPC endpoint, rather than an HTTP endpoint. The infrastructure is built around this difference, while maintaining principles from the CW20 and Secret implementations.

Architecture

erc20/contract-query.ts

• The base layer of the ERC-20 module—has the ability to query an ERC-20 contract for all relevant fields. The ObservableQueryERC20ContractData class parallels the ObservableCosmwasmContractChainQuery class for CW20s, and serves as an extendable object to fulfill contract requests.
• This file is lengthier than its counterparts because it requires additional infrastructure to fetch and parse ERC-20 contract data using the ObservableJsonRPCQuery class

erc20/erc20-balance.ts

• Connects the ERC-20 module to the extension's BalanceRegistry by wrapping ObservableQueryERC20ContractData, as a parallel to cw20-balance.ts

erc20/erc20-contract-info.ts

• Wraps ObservableQueryERC20ContractData to provide a tokenInfo() response, to match the behavior provided in cw20-contract-info.ts
• This class does not fetch balances and is used primarily when adding a new ERC-20 token in the UI

erc20/queries.ts

• Wraps ObservableQueryERC20ContractData to provide a root query object, similar to cosmwasm/queries.ts

erc20/transaction-client.ts

• Creates an Ethereum Tx client to interface with a chain's Ethereum JSON-RPC provider
• This class can format Ethereum Tx's, broadcast signed Tx's to the node, and wait for confirmation

erc20/types.ts

• Contains type definitions for the module

accounts/ethereum.ts

• This class is responsible for sending ERC-20 token transfers when requested by the UI. It uses Keplr's signEthereum and the erc20/transaction-client to do so.

Notes

Support has not yet been implemented for mobile.

Demo

Token Management
https://user-images.githubusercontent.com/11379797/194942357-f0efaefc-16cb-4107-99ab-a5fadf78dacc.mov
Token Transfer via EVM
https://user-images.githubusercontent.com/11379797/208807580-c6fedd5d-e972-443a-bdf4-b682abcb4f92.mov
IBC Transfer of ERC-20 Token
https://user-images.githubusercontent.com/11379797/209244773-860ebca7-4e4b-4e70-82ee-2c083f8d023c.mov

[Thunnini]

@keplr-wallet/store-etc is uploaded in npm, and also used in other projects as well. We cannot merge this PR when @keplr-wallet/store-etc is deleted

[Thunnini]

To be honest, showing only balance (without support transfer) to the user has alot of parts that we need to think about. Also, as of right now, this feature is only for evmos and if features being added start becoming domain specific, it becomes harder and harder to manage code. Current code needs to go through refactoring in the near future, so implementing a special feature is a huge burden in terms of code management. Also, I do think that current PR cycle is very slow, and that you might be unhappy about it.
The suggested way is the following: For evmos, instead of showing assets, we can try linking to your dashboard. This way I think we both can implement this faster and come to an stable agreement. I say we try this first and once this becomes stabilized, adding this feature to Keplr. What do you think of?

[Thunnini]

Please take off the restriction on the chain ID, unless there is a specific reason.

[0a1c]

Refactored to use the evmos-erc20 feature flag. The purpose for this condition is that Evmos supports sending ERC-20 tokens in IBC transactions, but other ERC-20 chains may not.

Let me know if this is not a concern, and we can remove the check.

[Thunnini]

Move this to account store

[0a1c]

I'm not sure what you mean. account/ethereum uses createERC20TokenTransferTx in transaction client, and createERC20TokenTransferTx uses createSignableEthereumTx.

Are you suggesting that account/ethereum calls createERC20TokenTransferTx in transaction client, which calls createSignableEthereumTx once again in account/ethereum?

[HeesungB]

@austinchandra Thank you for contribution!