Creates an abstract extension registry

* Factors out the common functionality of the Teiid Runtime Registry into
  an abstract class that can be extended by similar registry implementations
TEIIDDES-1739: Refactors the DDL importer

* Separates out the ddl importer into specialised node sub-importers

* Node Importers keys against the parser id returned from modeshape

* spi plugin provides the node importer registry and extension point
Scales back the manifest of ddl spi to Juno dependencies

* Since the ddl spi plugin was created using a Kepler TP, its minimum
  dependencies are based on Kepler. There is no real need and the plugin
  is inconsistent with other plugins.