chore: import upstream snapshot with attribution

grub2/set_default.cgi

@@ -0,0 +1,23 @@
+#!/usr/local/bin/perl
+# Set the saved GRUB 2 default boot entry.
+
+use strict;
+use warnings;
+require './grub2-lib.pl';    ## no critic
+
+our (%in, %text);
+
+&ReadParse();
+&error_setup($text{'runtime_err'});
+my %access = &get_module_acl();
+&error("$text{'eacl_np'} $text{'eacl_pruntime'}") if (!$access{'runtime'});
+
+# Runtime commands operate on the parsed generated menu index shown on index.cgi.
+my $entry = &grub2_entry_by_index($in{'idx'});
+&error($text{'runtime_eentry'}) if (!$entry);
+# The helper validates the selector before invoking grub-set-default.
+my $err = &grub2_run_entry_command('set_default_cmd', $entry);
+&error($err) if ($err);
+my $selector = &grub2_entry_selector($entry);
+&webmin_log("default", undef, $selector);
+&redirect("");