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/seg/sql/seg.sql

@@ -244,10 +244,14 @@ FROM test_seg WHERE s @> '11.2..11.3' OR s IS NULL ORDER BY s;
 
 SELECT str as seg,
        pg_input_is_valid(str,'seg') as ok,
-       pg_input_error_message(str,'seg') as errmsg
+       errinfo.sql_error_code,
+       errinfo.message,
+       errinfo.detail,
+       errinfo.hint
 FROM unnest(ARRAY['-1 .. 1'::text,
                   '100(+-)1',
                   '',
                   'ABC',
                   '1 e7',
-                  '1e700']) str;
+                  '1e700']) str,
+     LATERAL pg_input_error_info(str, 'seg') as errinfo;