+ Drop-Down menu is added when dataset excel template creation
+ Freezing top row added as well for the convenience of user
+ Some Java generics updates performed to eliminate some warnings in code
+ Code formatting & other minor updates
Refs: #16937
+ Drop-down menu items added for table templates
+ DstXls class is updated to inherit from TblXls class to prevent copy-paste errors (they have some same logic in code)
+ XlsServlet class updated to redirect error page when an exception occurs
+ XlsServletTest updated as well to conform changes
+ Java generics update & code formatting & removal of redundant interface implementation
Refs: #16937