Ignore launchpad deposit_data json file when loading keystores

Description

Users commonly copy all the files generated by the deposit-cli into their teku keys directory, including the deposit_data json file. Since it’s a .json file, Teku tries to load it as a keystore and fails to find a password file matching it resulting in confusing errors.

We should just ignore the deposit_data json file.

Sample content of deposit_data-1620858087.json:

[{"pubkey": "b93de474b36c68f1323b80d529220cbe868d876bf6be45259a2005159585f5154f8b24209dbbbf049ddadb9947a5e490", "withdrawal_credentials": "002c7560879a767d9d4447fda04b7a497af19cc80994d614557f7836fad6867b", "amount": 32000000000, "signature": "b552c4e2982d49cc626f284172ebf500478392980a0aa96b11e6a5c9f081cbd31bbf6cba503d1a3564dc5be9243311b203262f2863390eb483fb58b474527d91bbe5193e3c6e0d9f863c53c8ad0331e70f1180d1e730d4f46bbbfdaede0aa6a5", "deposit_message_root": "09b32e44c341c2977d8528af610e1adbbb249ce293133ae4a8b7c2a7d7afcfa0", "deposit_data_root": "9f88c0dedc95efa6be9048effa9a4376873078227f1ef9292f28683adc650b49", "fork_version": "00000121", "eth2_network_name": "altona", "deposit_cli_version": "1.1.0"}]%

We probably should check the content is at least vaguely like a deposit data file or at least not a keystore file before ignoring the file rather than just ignoring all deposit_data-*.json files.

[ajsutton]

@ajsutton - I was thinking of giving it a try. keystore json has crypto, kdf and cypher, If the current pair doesn’t have those keys in json, then probably ignore that json? Would that be a good check?

I’m inclined to go the other way and pick a few fields that do appear in the deposit file and ignore it specifically. We don’t want to silently ignore a file that the user added to the directory thinking it was a valid keystore, so generally better to fail. The deposit file just happens to be a very commonly added file which definitely shouldn’t be loaded so we want to explicitly filter it out.

But the basic idea of just checking if a couple of fields are present as part of the check is right. It doesn’t have to be a perfect check, just enough to avoid accidentally ignoring files we shouldn’t.

[ajsutton]

Fixed by #4085