## Issue Addressed
Resolve#1652
## Proposed Changes
Adds a cli option for voluntary exits. The flow is similar to prysm's where after entering the password for the validator keystore (or load password from `secrets` if present) the user is given multiple warnings about the operation being irreversible, then redirected to the docs webpage(not added yet) which explains what a voluntary exit is and the consequences of exiting and then prompted to enter a phrase from the docs webpage as a final confirmation.
Example usage
```
$ lighthouse --testnet zinken account validator exit --validator <validator-pubkey> --beacon-node http://localhost:5052
Running account manager for zinken testnet
validator-dir path: "..."
Enter the keystore password: for validator in ...
Password is correct
Publishing a voluntary exit for validator: ...
WARNING: This is an irreversible operation
WARNING: Withdrawing staked eth will not be possible until Eth1/Eth2 merge Please visit [website] to make sure you understand the implications of a voluntary exit.
Enter the phrase from the above URL to confirm the voluntary exit:
Exit my validator
Published voluntary exit for validator ...
```
## Additional info
Not sure if we should have batch exits (`--validator all`) option for exiting all the validators in the `validators` directory. I'm slightly leaning towards having only single exits but don't have a strong preference.
