dynamic creation of DB Table project variables

Allow dynamic creation of DB Table project variables.  Turn them into dynamic DDT variables:

  Project.Variables.AddVariable("MyDBTableVar", "DB Table");
  var1 = Project.Variables.VariableByName("MyDBTableVar");

  // Use DDT Driver paradigm.  Initialize variable like DDT.
  var1.ADODriver(ConnectionString, TableName);
  var1.CSVDriver(Filename);
  var1.ExcelDriver(Filename, Sheet, UseACEDriver);