Automate validator accounts backup

[pablomendezroyo]

🚀 Feature Request

Description

Hi there is Pablo from DAppNode.

The process of exporting the validator keys is done with validator accounts backup command through the validator CLI, where you get into an interactive terminal to select the validator to be exported and set the new password. This is great but not enough if you want to automate the process of exporting the validator.

Describe the solution you'd like

There are two values that need to be selected in the interactive terminal to finish the validator accounts backup: which validator and new password. In order to provide a way to automate this process would be great to include a flag for each option, such as:
--validator-name
--validator-backup

[pablomendezroyo]

Just found the way asking in Discord
For anyone curious:

validator accounts backup --wallet-password-file=/tmp/pass.txt --backup-dir=/tmp/out --backup-password-file=/tmp/pass.txt --backup-public-keys=0xb3295a8de96b2b21c14e89d32a8772ad06d635ed0bbfcbb62bc3fc3e90c4f737ae755bb6beda08ea8e63cd7877316ca4