Support different passwords for each keystore

**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](https://docs.teku.consensys.net/Reference/CLI/CLI-Syntax/#validator-keys) work.

I could imagine a file structure like this

```txt
:
:
:
```