Merge javasrc2cpg and jimple2cpg

Let's merge the two frontends to have a single cpg with both the source and classes from the jars. In addition, retain the `META-INF/MANIFEST.MF` file as a config file so that the jar's group, name, and version can be reconstructed to identify the source along with the file name.

Here is some messy logic showing this parsing in action - https://github.com/CycloneDX/cdxgen/blob/master/utils.js#L4516