Create guides and scripts for individual stakers

[mksh]

Right now eth-staking-smith is catering to the SaaS use-case mostly, but there is also a possibility of use by individual stakers who care of different security and usability benefits.

To support individual staker use-case, we need to add guides that instruct how to use eth-staking-smith with Launchpad, and scripts that

• split keystore out of sensitive data
• make sure only keystore is stored on HDD
• show mnemonic on screen
• destroy mnemonic and private key(s) after the run