Add padding at bottom of edit component page

Previously, the save floating action button was overlapping truth table.
Now, the screen can be scrolled such that the button will no longer
overlap due to the new empty space.

lib/pages/edit_component.dart

@@ -373,6 +373,9 @@ class EditComponentPage extends HookWidget {
                 ),
               )
             ],
+            const SliverPadding(
+              padding: EdgeInsets.only(bottom: 56 + 16 + 16),
+            ),
           ],
         ),
         floatingActionButton: !dirty ? null : FloatingActionButton(