Replace LookupFuncNameTypeNames() with LookupFuncWithArgs()

The old function took function name and function argument list as
separate arguments.  Now that all function signatures are passed around
as ObjectWithArgs structs, this is no longer necessary and can be
replaced by a function that takes ObjectWithArgs directly.  Similarly
for aggregates and operators.

Reviewed-by: Jim Nasby <Jim.Nasby@BlueTreble.com>
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

src/include/nodes/parsenodes.h

@@ -2418,9 +2418,7 @@ typedef struct CreateOpClassItem
 {
 	NodeTag		type;
 	int			itemtype;		/* see codes above */
-	/* fields used for an operator or function item: */
-	List	   *name;			/* operator or function name */
-	List	   *args;			/* argument types */
+	ObjectWithArgs *name;		/* operator or function name and args */
 	int			number;			/* strategy num or support proc num */
 	List	   *order_family;	/* only used for ordering operators */
 	List	   *class_args;		/* amproclefttype/amprocrighttype or
@@ -2730,8 +2728,7 @@ typedef struct AlterOwnerStmt
 typedef struct AlterOperatorStmt
 {
 	NodeTag		type;
-	List	   *opername;		/* operator name */
-	List	   *operargs;		/* operator's argument TypeNames */
+	ObjectWithArgs *opername;	/* operator name and argument types */
 	List	   *options;		/* List of DefElem nodes */
 } AlterOperatorStmt;