chore: import upstream snapshot with attribution

usermin/change_theme.cgi

@@ -0,0 +1,29 @@
+#!/usr/local/bin/perl
+# change_theme.cgi
+# Change the current webmin theme
+
+require './usermin-lib.pl';
+$access{'themes'} || &error($text{'acl_ecannot'});
+&ReadParse();
+
+&lock_file($usermin_config);
+&get_usermin_config(\%uconfig);
+$uconfig{'theme'} = $in{'theme'};
+&put_usermin_config(\%uconfig);
+&unlock_file($usermin_config);
+
+&lock_file($usermin_miniserv_config);
+&get_usermin_miniserv_config(\%miniserv);
+if ($in{'theme'}) {
+	$miniserv{'preroot'} = $in{'theme'};
+	}
+else {
+	delete($miniserv{'preroot'});
+	}
+&put_usermin_miniserv_config(\%miniserv);
+&unlock_file($usermin_miniserv_config);
+&restart_usermin_miniserv();
+&webmin_log('theme', undef, undef, \%in);
+
+&redirect("");
+