Rework pg_input_error_message(), now renamed pg_input_error_info()

pg_input_error_info() is now a SQL function able to return a row with
more than just the error message generated for incorrect data type
inputs when these are able to handle soft failures, returning more
contents of ErrorData, as of:
- The error message (same as before).
- The error detail, if set.
- The error hint, if set.
- SQL error code.

All the regression tests that relied on pg_input_error_message() are
updated to reflect the effects of the rename.

Per discussion with Tom Lane and Andrew Dunstan.

Author: Nathan Bossart
Discussion: https://postgr.es/m/139a68e1-bd1f-a9a7-b5fe-0be9845c6311@dunslane.net

contrib/isn/sql/isn.sql

@@ -110,11 +110,15 @@ SELECT '12345679'::ISSN = '9771234567003'::EAN13 AS "ok",
 -- test non-error-throwing input API
 SELECT str as isn, typ as "type",
        pg_input_is_valid(str,typ) as ok,
-       pg_input_error_message(str,typ) as errmsg
+       errinfo.sql_error_code,
+       errinfo.message,
+       errinfo.detail,
+       errinfo.hint
 FROM (VALUES ('9780123456786', 'UPC'),
              ('postgresql...','EAN13'),
              ('9771234567003','ISSN'))
-      AS a(str,typ);
+      AS a(str,typ),
+     LATERAL pg_input_error_info(a.str, a.typ) as errinfo;
 
 --
 -- cleanup