generator-jhipster: JDL App generation is broken, again

The new JDL app generation support is broken, below are the issues

The parser expects, appType, DB and basename to be passed, which is not logical for app generation as it needs to be inferred from the app config
The import-jdl sub gen expects a .yo-rc.json when generating applications, it should be skipped
The path option is not required and might cause issues(especially in JH online), it needs to be removed as we really don’t need it, and for microservices, we could always create folders from the current directory
When the app config is created it needs to call the app generator to create the actual source code as well

About this issue

I’ve just released v3. Here are the done things/issues (you can see them in the coming PR):

No app & only entities -> creates .jhipster folder with the entities and generates them. No issue here
One app & entities -> creates a .yo-rc.json and a .jhipster folder with the entities, does not generate anything because I don’t get why Yeoman wouldn’t let me compose the app & the entity generators as I want (maybe a priority issue, and I may not call the app generator correctly)
More than one app & entities, once I get the second one, I don’t expect it to be too difficult a thing to do.