Abstract and further merge filter menus

Summary:
  - Adds `PhabricatorMenuItemView` which is a non-hacky object representing a single menu item.
  - Adds `PhabricatorMenuView`, a collection of items.
  - Deletes some busted/old interfaces full of garbage nonsense.
  - Merges menu item styles from `aphront-side-nav-view-css` and `phabricator-nav-view-css`. These are old-style and new-style rules which got partially updated recently.
    - The new-style menus have a darker background (#ececec) than the old-style menus (#f7f7f7) so some of the highlight/hover colors weren't visible. I shuffled them around but something or other might need further adjustment.

Test Plan: looked at every menu I could

Reviewers: chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T1960

Differential Revision: https://secure.phabricator.com/D4036

src/applications/owners/controller/PhabricatorOwnersListController.php

@@ -308,17 +308,9 @@ final class PhabricatorOwnersListController
     return $panel;
   }
 
-  protected function getExtraPackageViews() {
-    switch ($this->view) {
-      case 'search':
-        $extra = array(array('name' => 'Search Results',
-                             'key'  => 'view/search'));
-        break;
-      default:
-        $extra = array();
-        break;
+  protected function getExtraPackageViews(AphrontSideNavFilterView $view) {
+    if ($this->view == 'search') {
+      $view->addFilter('view/search', 'Search Results');
     }
-
-    return $extra;
   }
 }