MCOL-507 Further ExeMgr performance improvements

This does the following:

* Switch resource manager to a singleton which reduces the amount of
times the XML data is scanned and objects allocated.
* Make the I_S tables use the FE implementation of the system catalog
* Make the I_S.columnstore_columns table use the RID list cache
* Make the extentmap pre-allocate a vector instead of many small allocs

dbcon/ddlpackageproc/ddlindexpopulator.cpp

@@ -65,7 +65,7 @@ namespace ddlpackageprocessor
   {
     CalpontSelectExecutionPlan csep;
     makeCsep(csep);
-    ResourceManager rm;
+    ResourceManager *rm;
     if (! fEC) 
     {
 		fEC = DistributedEngineComm::instance(rm);