Fix path delimiters in connection string on Windows

The temporary path generated in commit c113d8ad5 cannot be passed as-is in
the connection string on Windows since the path delimiting backslashes will
be treated as escape characters. Fix by converting backslash to slash as in
similar path usecases in other tests.

Reported-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20211202195130.e7pprpsx4ell22sp@alap3.anarazel.de

src/test/ssl/t/001_ssltests.pl

@@ -56,6 +56,7 @@ foreach my $keyfile (@keys)
 	chmod 0600, "$cert_tempdir/$keyfile"
 	  or die "failed to change permissions on $cert_tempdir/$keyfile: $!";
 	$key{$keyfile} = PostgreSQL::Test::Utils::perl2host("$cert_tempdir/$keyfile");
+	$key{$keyfile} =~ s!\\!/!g if $PostgreSQL::Test::Utils::windows_os;
 }
 
 # Also make a copy of that explicitly world-readable.  We can't
@@ -67,7 +68,7 @@ copy("ssl/client.key", "$cert_tempdir/client_wrongperms.key")
 chmod 0644, "$cert_tempdir/client_wrongperms.key"
   or die "failed to change permissions on $cert_tempdir/client_wrongperms.key: $!";
 $key{'client_wrongperms.key'} = PostgreSQL::Test::Utils::perl2host("$cert_tempdir/client_wrongperms.key");
-
+$key{'client_wrongperms.key'} =~ s!\\!/!g if $PostgreSQL::Test::Utils::windows_os;
 #### Set up the server.
 
 note "setting up data directory";

src/test/ssl/t/002_scram.pl

@@ -102,6 +102,7 @@ copy("ssl/client.key", "$cert_tempdir/client_scram.key")
   "couldn't copy ssl/client_key to $cert_tempdir/client_scram.key for permission change: $!";
 chmod 0600, "$cert_tempdir/client_scram.key"
   or die "failed to change permissions on $cert_tempdir/client_scram.key: $!";
+$client_tmp_key =~ s!\\!/!g if $PostgreSQL::Test::Utils::windows_os;
 $node->connect_fails(
 	"sslcert=ssl/client.crt sslkey=$client_tmp_key sslrootcert=invalid hostaddr=$SERVERHOSTADDR dbname=certdb user=ssltestuser channel_binding=require",
 	"Cert authentication and channel_binding=require",

src/test/ssl/t/003_sslinfo.pl

@@ -44,6 +44,7 @@ copy("ssl/client_ext.key", "$cert_tempdir/client_ext.key")
   "couldn't copy ssl/client_ext.key to $cert_tempdir/client_ext.key for permissions change: $!";
 chmod 0600, "$cert_tempdir/client_ext.key"
   or die "failed to change permissions on $cert_tempdir/client_ext.key: $!";
+$client_tmp_key =~ s!\\!/!g if $PostgreSQL::Test::Utils::windows_os;
 
 #### Set up the server.