MDL-81512 core_theme: Reinstate theme category as custom theme settings

admin/settings/appearance.php

@@ -349,6 +349,7 @@ if ($hassiteconfig or has_any_capability($capabilities, $systemcontext)) { // sp
         new lang_string('themeselector', 'admin'), $CFG->wwwroot . '/admin/themeselector.php'));
 
     // Settings page for each theme.
+    $ADMIN->add('appearance', new admin_category('themes', new lang_string('themesettingscustom', 'admin')));
     foreach (core_component::get_plugin_list('theme') as $theme => $themedir) {
         $settingspath = "$themedir/settings.php";
         if (file_exists($settingspath)) {

lang/en/admin.php

@@ -1458,6 +1458,7 @@ $string['themeresetcaches'] = 'Clear theme caches';
 $string['themeselect'] = 'Change theme';
 $string['themeselector'] = 'Themes';
 $string['themesettingsadvanced'] = 'Advanced theme settings';
+$string['themesettingscustom'] = 'Custom theme settings';
 $string['themeeditsettingsname'] = 'Edit theme settings \'{$a}\'';
 $string['themesettingsname'] = 'Theme settings \'{$a}\'';
 $string['themeusagereportname'] = 'Theme usage report \'{$a}\'';