Implement system checks

[remyroy]

System checks to test if the machine is good enough for staking would be interesting. We could copy or take some of the checks that are done with eth-wizard for instance. See https://github.com/stake-house/eth-wizard/blob/539ad1e6879d7577b55d51f5417c7b8c77a8ee4e/ethwizard/platforms/ubuntu/install.py#L471

• Available disk space above 900 GB
• Substained disk IOPS: read above 3k, write above 1k
• Installed RAM above 12 GB
• Internet speed: down above 4.5 MBS, up above 4.5 MBS

All those values are up for debate.