[feature request] Add the ability to generate BLS change using the deposit-data and keystore files generated by staking-deposit-cli

[yzhuang]

Some users have forgotten their mnemonic but saved their deposit-data and keystore files.

[Sphearis]

Is that even possible? You can get validators private keys from those but how would you get the withdrawal ones from that point?

[remyroy]

Some users have forgotten their mnemonic but saved their deposit-data and keystore files.

It's not possible to add a withdrawal address or to generate a BLS change with the deposit-data or keystore file. You really need the mnemonic.