Webgui: Add clear filter function

webgui/maintenance.php

@@ -32,6 +32,11 @@ switch ($submit = form_get_action()) {
         $action = ACT_DEFAULT;
         break;
 
+    case 'freset':
+        db_clear_filter(204);
+        $action = ACT_DEFAULT;
+        break;
+
     case 'insert':
         $p[':vid'] = $user->vid;
         $p[':eid'] = gpc_get_int($_POST, 'eid');
@@ -96,6 +101,7 @@ foreach ($opt_special + $opt_equipment as $k => $v) {
 <label for="flt_txt">Text</label>
 <input type="text" name="flt_txt" size="15" maxlength="30" value="<?=$flt->txt ?? ''?>">
 <button name="submit[filter]" class="btn btn-sm btn-primary" title="<?=_('Apply')?>"><?=_('Go')?></button>
+<button name="submit[freset]" class="btn btn-sm btn-secondary float-end" title="<?=_('Reset filter to defaults')?>"><?=_('Clear')?></button>
 </div>
 </div>
 </form>