Rework option set of oid2name

oid2name has done little effort to keep an interface consistent with
other binary utilities:
- -H was used instead of -h/-host.  This option is now marked as
deprecated, still its output is accepted to be backward-compatible.
- -P has been removed from the code, and was still documented.
- All options gain long aliases, making connection options more similar
to other binaries.
- Document environment variables which could be used: PGHOST, PGPORT and
PGUSER.

A basic set of TAP tests is added on the way, and documentation is
cleaned up to be more consistent with other things.

Author: Tatsuro Yamada
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/c7e7f25c-1747-cd0f-9335-390bc97b2db5@lab.ntt.co.jp

contrib/oid2name/t/001_basic.pl

@@ -0,0 +1,12 @@
+use strict;
+use warnings;
+
+use TestLib;
+use Test::More tests => 8;
+
+#########################################
+# Basic checks
+
+program_help_ok('oid2name');
+program_version_ok('oid2name');
+program_options_handling_ok('oid2name');