Clean up the Diffusion search UI a little bit

Summary:
Ref T156. @vlada recently implemented filename search in Diffusion, this cleans up the UI a little bit:

  - Instead of showing one search box with two different buttons, let the submit buttons appear to the right of the text boxes and separate the search modes.
  - Clean up the results a little bit (don't show columns which don't exist).

Test Plan: {F107260}

Reviewers: vlada, btrahan, chad

Reviewed By: chad

CC: vlada, chad, aran

Maniphest Tasks: T156

Differential Revision: https://secure.phabricator.com/D8125

src/applications/diffusion/controller/DiffusionBrowseMainController.php

@@ -9,8 +9,9 @@ final class DiffusionBrowseMainController extends DiffusionBrowseController {
     // Figure out if we're browsing a directory, a file, or a search result
     // list. Then delegate to the appropriate controller.
 
-    $search = $request->getStr('grep');
-    if (strlen($search)) {
+    $grep = $request->getStr('grep');
+    $find = $request->getStr('find');
+    if (strlen($grep) || strlen($find)) {
       $controller = new DiffusionBrowseSearchController($request);
     } else {
       $results = DiffusionBrowseResultSet::newFromConduit(