LibGUI+FileManager: Misc tweaks courtesy of clang-format

Author: https://github.com/bugaevc
Commit: 10324f95b0
Pull-request: https://github.com/SerenityOS/serenity/pull/1050

Libraries/LibGUI/GModelSelection.h

@@ -50,7 +50,7 @@ public:
 
         for (auto& index : m_indexes)
             selected_indexes.append(index);
-            
+
         return selected_indexes;
     }