Improve application query UI/UX

Summary:
Ref T2625. @chad, you might have some feedback here. The behaviors this implements are:

  - When the user selects "Advanced Search", we show the full search UI and no results (for performance and clarity).
  - When the user submits a search which //is not// a named search, we show the full search UI and the "Save Custom Query..." button.
  - When the user submits a search which //is// a named search, we show "Results for search X." with an "Edit Query..." button. The button expands the search form.
  - When the user selects a builtin query (like "All Pastes"), we don't show any search UI, but I'm probably going to make this behave more like named searches.

Test Plan:
{F44346}

{F44347}

Reviewers: chad, btrahan, blc

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2625

Differential Revision: https://secure.phabricator.com/D6063

src/applications/paste/controller/PhabricatorPasteController.php

@@ -32,7 +32,7 @@ abstract class PhabricatorPasteController extends PhabricatorController {
     $nav->addFilter('savedqueries', pht('Edit Queries...'));
 
     $nav->addLabel(pht('Search'));
-    $nav->addFilter('filter/advanced', pht('Advanced Search'));
+    $nav->addFilter('query/advanced', pht('Advanced Search'));
 
     $nav->selectFilter(null);