Is your feature request related to a problem? Please describe.

There are two flags: --importKeystores and --importKeystoresPassword. Where --importKeystores expects a directory with all the keystores while --importKeystoresPassword expects just ONE password file to decrypt ALL the keystores. What if we have keystores with different password for each keystore?

Describe the solution you'd like

Support multiple password file formats (simple and mapped) or option to provide multiple password files, maybe similar approach to how teku validator-keys work.

I could imagine a file structure like this

<keystore filename1>:<password1>
<keystore filename2>:<password2>
<keystore filename3>:<password3>