Replace '--generator-name' with multiple switches to select a generator

Created by: jmini

On the long term we might want to offer an other way to select the targeted generator.

Probably with multiple switches (to be defined more precisely):

Examples:

cli -type=client -language=kotlin
cli -type=server -language=kotlin -framework=ktor

A first step in this direction was made with #39 (closed), where we have renamed -l (--lang) into -g (--generator-name).

With the next version (4.0.0 ?) we might want to continue to work on this by providing an other way to lookup a generator with multiple switches.

This is open for feedback.