Add option to override csrconfig values via cli

[esynr3z]

It would be nice to have a way to override configuration parameters via CLI.
This facilitates scripting and experimenting around tool without modifying the configuration file.

It is quite a general feature that improves user experience with any configfile-oriented tools (which Corsair is). It also greatly simplifies CI, because otherwise when some tweaked configuration is required you either have to have multiple configuration files stored or modify it on-flight following parse-modify-dump flow.

Interface for that feature could be quite simple and could follow the same pattern used in git config. Consider this

git config --global user.email "[email protected]"

So user.emal is actually section and key within configuration file.

This would work for Corsair too. Following can override original parameters for the current run without touching the file:

corsair --set-config globcfg.base_address 0x1000 --set-config adoc.print_conventions false