Disable lock and group buttons when selected item is not CanvasItem

[jsjtxietian]

An idea of fix #88939 , should be merged after #89132 is merged.

The origin problem lies in the fact that ParallaxBackground is not a CanvasItem so the code did not do anything special to it, I guess if this need to be fixed, we can either hide the button or make it disable.

This pr disables lock and group buttons when there's not any selected CanvasItem.

[Mickeon]

So what about Node3Ds?

[KoBeWi]

While the report was only about 2D editor, the 3D one needs the same treatment, even for consistency.

[jsjtxietian]

I've rebased the code onto master, and added back _update_lock_and_group_button in _draw_viewport, to support update the lock button immediately after click it instead of next selection_changed.

[KoBeWi]

When you click non-CanvasItem node, the lock button opens:

godot.windows.editor.dev.x86_64_aaHzgY3HQv.mp4

It's inconsistent with empty selection, which is closed, and also suggests that non-CanvasItems are "locked". Probably worth fixing. It can be done with all_locked = all_locked && has_canvas_item.

EDIT:
Same in 3D.

[akien-mga]

Thanks!