CLI option to set basic config

[flying-sausages]

Is your feature request related to a problem? Please describe.
The only way to programmatically set the Calibre library path is via a POST to the /basicconfig endpoint, which has just moved from /config.

Also, it would be nice to be able to set this without having to depend on the web interface.

Describe the solution you'd like
Like there's an -s flag to change a user's password, a flag for --library or -l with a path parameter or something like that would be super useful.

Describe alternatives you've considered
POSTing against the endpoint, but that seems to change every other version.

curl -sk 'http://127.0.0.1:8083/basicconfig' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' --compressed -H 'Content-Type: application/x-www-form-urlencoded' -H 'Connection: keep-alive' \
            --data-urlencode "config_calibre_dir=$CALIBRE_LIBRARY_PATH" \
            --data-urlencode "submit="

Additional context
Encompassed by #1427 possibly? This is more granular and specific.

[OzzieIsaacs]

Also related to #1656.

This sounds like a good idea.

[samyak-jain]

I don't think the linked issue has tackled this particular problem. @OzzieIsaacs Is this something you mind me picking up?

[OzzieIsaacs]

Feel free to create a PR