rect_scale not updated live in inspector

[johnfn]

Godot version:
3.3

OS/device including version:
MacOS Catalina

Issue description:
Control > Rect > Scale does not update when I scale a control.

Steps to reproduce:

1. Create a control node (I used Label)
2. Scale the control node with the scale tool
3. Look at Control> Rect > Scale in the inspector. It still says x: 1, y: 1

If you save and reopen the scene, the scale is updated properly.

Minimal reproduction project:

This reproduces in an empty project.

[Calinou]

This is likely an issue with change_notify() or update() not being called in the scale tool gizmo in editor/canvas_item_editor_plugin.cpp. Note that Node2D and Control scaling go through different code paths.

Since change_notify() was removed in favor of polling in the master branch, this issue is likely only present in the 3.x branch.

[phil-shenk]

_change_notify("rect_scale") seems to be missing in Control::set_scale in control.cpp (in 3.3 at least). PR incoming

[akien-mga]

Fixed by #48957.