Apply clamp_to_embedder on parent resize and popup.

Fixes #75084.

The clamp_to_embedder setting was added in 8be16e0704,
but was not set on any of the in-editor dialogs.

This patch sets `clamp_to_embedder` on editor dialogs so they cannot be dragged out of the frame.
This also modifies `clamp_to_embedder` so a window is clamped to the bounds of an embedder when
it pops up and when the parent is resized.

editor/editor_settings_dialog.cpp

@@ -698,6 +698,7 @@ void EditorSettingsDialog::_bind_methods() {
 
 EditorSettingsDialog::EditorSettingsDialog() {
 	set_title(TTR("Editor Settings"));
+	set_clamp_to_embedder(true);
 
 	tabs = memnew(TabContainer);
 	tabs->set_theme_type_variation("TabContainerOdd");