Removes eclipse dependencies from teiid runtime client plugin

* Creates an eclipse.teiid.client fragment for providing the TeiidDriver
  to eclipse's datatools framework

* org.komodo.teiid.client
 * Adds saxonhe back as a library rather than depending on the eclipse
   version
 * Adds to Admin interface a getDataSourceDrivers method, responsible for
   returning a collection of the installed datasource drivers in the host
   server. Effectively pushes down to the teiid implementation the logic
   of getDSMatchForDriverClass from ExecutionAdmin
 * getDataSourceDrivers was never supported by teiid 7 and this is
   formalised with use of the AdminSpec implementations
 * TeiidRuntimePlugin removed as the activator and its functionality
   reassigned to eclipse client fragment
 * ExecutionAdmin now has its own refresh thread for waiting on deployed
   vdbs. Currently untested and a prototype so may have issues down the line

* org.komodo.spi
 * Removes getRuntimePluginPath from interface as only relevant to eclipse
   datatools
 * IDataSourceDriver interface for wrapping the driver properties installed
   in the teiid hosted server