TEIIDDES-1751: Provide api for getting client-side Teiid Driver

 * Rather than fetching the Teiid Driver from the Teiid Server, requiring
   connection, the driver is available in each client runtime plugin. For
   cases where only the driver is required, eg. Database Developer connections,
   provide the driver.

 * To allow for changes in the Teiid Driver, each runtime will provide its
   own version through the ExecutionAdminFactory so that the correct driver
   for the server is provided.

 * ModelerCore
  * Stop providing access to the default teiid server since it could well
    be null and invite null pointer exceptions.
  * Provides an API for the relevent properties of the default server
    requested by clients and handle the possibilty of the default server
    being null.