promtool check-metrics: bits vs bytes

[mdlayher]

Creating a new issue from the discussion in: #2605.

Some of the current open questions:

• Should this tool provide both "errors" and "warnings"?
• Do warnings vs. errors make the tool less useful for CI purposes?
• Does it make for network metrics or metrics such as "available bits of entropy" to remain as bits instead of bytes?
• Can the conversion for humans just be handled by a tool like Grafana, or multiplying/dividing by 8 where needed?

Feel free to continue the discussion here.

[grobie]

From @brian-brazil:

If the choice is between allowing a mix of bit and bytes, and having an exception for entropy I say we switch entropy to bytes.