[#62106126] Implements schema_exists? on jdbc_connection
[#62106126] User can browse JDBC data source datasets

 - datasets are now browsable within a jdbc schema
 - for jdbc_onnection
  -> Implements #datasets/#tables/#views for jdbc_connection.
  -> Implements table_exists?/view_exists? for jdbc_connection
  -> Stubs datasets_count and metadata_for_dataset, needs implementation
 - the monkey patch on Sequel::Jdbc::Database has expanded to facilitate passing
   options to the jdbc getTables method, rather than sending nil for everything
   as Sequel is doing by default.
  -> return arrays of hashes with :name, :type keys similar to the querys for gp/orcl
  -> will likely need to do something similar for schemas so everything is not downcase'd
     and symbolized (result of Sequel's #output_identifier_meth)