Research Etherscan & BlockScout APIs to confirm priority list offering

[konstantinabl]

** Description **

Research possibilities for implementation for the endpoint mentioned in the main description of the EPIC

Tasks

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1. Research etherscan endpoints
2. Research blockscout endpoints

[konstantinabl]

Etherscan findings:

1. https://docs.etherscan.io/api-endpoints/blocks#get-block-and-uncle-rewards-by-blockno - no point in implementing this, since in Hedera there are no concept of uncles or block rewards
2. https://docs.etherscan.io/api-endpoints/accounts#get-a-list-of-erc721-token-transfer-events-by-address - can be easily implemented using the contract/logs endpoint in the MN API. Need to identify erc721 tokens by using the new ERC Registry or sevm lib.
3. https://docs.etherscan.io/api-endpoints/accounts#get-a-list-of-erc1155-token-transfer-events-by-address - same as above with the only difference identifying 1155 contracts may not be so straightforwards

Blockscout findings:

1. https://docs.blockscout.com/devs/apis/rpc/block#get-block-reward-by-block-number - again not applicable
2. https://docs.blockscout.com/devs/apis/rpc/account#get-token-transfer-events-by-address - imo this endpoint is similar to this in etherscan https://docs.etherscan.io/api-endpoints/accounts#get-a-list-of-erc20-token-transfer-events-by-address and thus it is possible to implement it in a similar way to the erc721 transfer list
3. https://docs.blockscout.com/devs/apis/rpc/account#get-list-of-tokens-owned-by-address - i believe this would be very hard to implement. Blockscout are using a DB, so its easy for them to display this info. For us however, its more complicated since balances of erc-20 tokens are stored in the contract itself, meaning we need to either track all transfers into an account and somehow calculate what went out and what went in OR scan all erc-20s, call erc20.balanceOf(). All of this is very expensive and may not be worth it