Request: CLI: better input validation of settings

[onnozweers]

Hi all,

First of all, thanks for Meshcore, I absolutely love it!

It appears that everything that starts with path.hash.mode is treated as path.hash.mode.

> get path.hash.mode
> 2
> get path.hash.mode.thisoptiondoesnotexist
> 2
> get path.hash.mode.min
> 2

This is quite confusing, because there is this open PR #2707 with a new setting, path.hash.mode.min. I was trying out some forks of Meshcore firmware to check if they had implemented this new setting already. When I got a valid reply, I was completely put on the wrong track.

Could validation be improved, so that wrong settings lead to an error message?

Thanks!