Return true if a query is present
This function returns true if this contains a query. An empty query is distinct from having no query.
assert( url_view( "/sql?id=42&col=name&page-size=20" ).has_query() );
query = *( pchar / "/" / "?" )
query-param = key [ "=" value ]
query-params = [ query-param ] *( "&" query-param )
encoded_params , encoded_query , params , query .