WIP Refactor generating rules and rule repositories

[mwz]

This PR refactors how rules and rule repositories are generated.

My goal is to be able to export the collection of all of our raw rules (as they get generated directly from Scalastyle and Scapegoat) and the rule repositories and quality profiles that get created by sonar-scala at runtime. I want to be able to export all of that data into a json file, which I can then use in a separate user interface embedded on sonar-scala.com website, as described in #343.

In order to do that, I created a new package metadata, which will contain (in an intermediate data format) all of the rules, repositories and quality profiles. This data is then going to be used to

• create rule repositories and quality profiles at runtime when SonarQube starts up
• and it will also allow me to export it to a json file using a separate cli tool, which can be run on its own - see the sonar-scala-metadata.json file for the output.

So far I've refactored Scalastyle's rule repository to use this new mechanism and I still have Scapegoat and all the quality profiles left to do. I don't think I want to create a massive PR with all the changes in it, so as long as it's in a working state, I will refactor this functionality incrementally, e.g. Scalastyle quality profile next, then Scapegoat rules repo, quality profile and then all the other quality profiles.

I still need to add some of the new files to the plugin context, so that SonarQube doesn't blow up at runtime.

Relates to #343.

[BalmungSan]

Pretty cool.

Maybe the generator could / should be moved to another module? But probably just too much extra work for just not including it in the sonar-scala.jar

[mwz]

Maybe the generator could / should be moved to another module?

I thought about it doing it and It's not a big deal thb - I might still do it, but it's not the end of the world if this little app gets bundled into the same artifact.

[mwz]

I still need to add some of the new files to the plugin context, so that SonarQube doesn't blow up at runtime.

It looks like I don't need to declare anything new in the context, I think this is ready to be merged.