InputMapEditor control is not updated when adding actions in tool mode

[me2beats]

Godot version:

3.2.3

OS/device including version:

Windows

Issue description:

tool
extends Control

func _ready():
    InputMap.add_action("test")
    print (InputMap.has_action("test"))

After running this, I can see

True

In Output
But I don't see new action in InputMap list (Project-ProjectSetting-InputMap).

And when I reopen the project, the input data (new test action) is lost.

Steps to reproduce:

1. Create a project
2. Create a node (in this example I use Control) and attach the script above.
3. Save the script and reopen the scene (for triggering the Control _ready())
   now True should be printed in Output
4. Select Project - ProjectSettings - InputMap to open InputMap window.
   As you can see, new test action is not added.

Minimal reproduction project:

[AnidemDex]

Still happens in Godot 3.4.2

[AnidemDex]

Additional note: You can add actions from plugins, but they're only visible when you restart the editor

[alazifk]

Same thing happens in Godot 4.0. InputMap.add_action() appears to be broken.

[Calinou]

Thanks for the report! Consolidating in #25865.