Fix various typos in code and tests

Most of these are recent, and the documentation portions are new as of
v16 so there is no need for a backpatch.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20230208155644.GM1653@telsasoft.com

src/test/regress/sql/create_procedure.sql

@@ -42,7 +42,7 @@ CALL ptest1s('b');
 
 SELECT * FROM cp_test ORDER BY b COLLATE "C";
 
--- utitlity functions currently not supported here
+-- utility functions currently not supported here
 CREATE PROCEDURE ptestx()
 LANGUAGE SQL
 BEGIN ATOMIC