### Godot version

Godot 4, d1e5903c67956707948b1de370b807e3aad395b7

### System information

Arch Linux, Gnome Shell, Wayland

### Issue description

The "(Re)importing Assets" dialog blocks all other windows while importing is in progress. This window is always on top, immovable, and unhideable. For long import operations it makes using other applications on the system difficult.

![Screenshot from 2023-01-27 00-39-51](https://user-images.githubusercontent.com/6334580/215018181-41c17f90-140b-4b86-8d62-3515accdf3a7.png)

![Screenshot from 2023-01-27 00-40-26](https://user-images.githubusercontent.com/6334580/215018190-e2f26c78-1260-4499-8ca7-9146c260a6d0.png)

![Screenshot from 2023-01-27 00-44-18](https://user-images.githubusercontent.com/6334580/215018197-850ab0c3-f5e4-47b6-babf-771851d5a876.png)


### Steps to reproduce

Cause files to import, try to use other applications while import is in progress.

### Minimal reproduction project

N/A
if (MessageQueue::get_singleton()->is_flushing()) {
		ERR_PRINT("Do not use progress dialog (task) while flushing the message queue or using call_deferred()!");
		return;
	}
	ERR_FAIL_COND_MSG(tasks.has(p_task), "Task '" + p_task + "' already exists.");
	ProgressDialog::Task t;
	t.vb = memnew(VBoxContainer);
	VBoxContainer *vb2 = memnew(VBoxContainer);
	t.vb->add_margin_child(p_label, vb2);
	t.progress = memnew(ProgressBar);
	t.progress->set_max(p_steps);
	t.progress->set_value(p_steps);
	vb2->add_child(t.progress);
	t.state = memnew(Label);
	t.state->set_clip_text(true);
	vb2->add_child(t.state);
	main->add_child(t.vb);
	tasks[p_task] = t;
	if (p_can_cancel) {
		cancel_hb->show();
	} else {
		cancel_hb->hide();
	}
	cancel_hb->move_to_front();
	canceled = false;