Add search bar to SearchActivity.

Styling doesn't look exactly right yet but there's a bar.
Creates an ItemDecoration to add a spacer above the first view.

Removes the action bar and replaces it with a SearchView
inside of a CardView.

Remaining work: pixel pushing

Bug: 37477506
Test: make RunSettingsRoboTests
Change-Id: I4a0f0c91c51ff5820b61a596520d80a3337c3466
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 8a50b01..f8df82e 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -209,7 +209,8 @@
         <activity android:name=".search.SearchActivity"
                   android:label="@string/search_settings"
                   android:icon="@drawable/ic_search_history"
-                  android:parentActivityName="Settings">
+                  android:parentActivityName="Settings"
+                  android:theme="@style/Theme.Settings.NoActionBar">
         </activity>
 
         <!-- Top-level settings -->