Godot: Version control window lists all global classes

[Xrayez]

Godot version:
3.2-alpha, 24e1039

OS/device including version:
Windows 10

Issue description:
When attempting to select a VCS, all global classes exposed via class_name are listed regardless:

Steps to reproduce:

1. Create global classes with class_name
2. Go to Project → Version Control → Set Up Version Control
3. See all classes listed in the project.

Minimal reproduction project:
vcs-global-classes.zip

[Calinou]

I can confirm this on commit https://github.com/godotengine/godot/commit/24e1039eb6fe32115e8d1a62a84965e9be19a2ed.

[Zylann]

I wonder what kind of VCS Select an available VCS is

[Xrayez]

Likely this Git plugin, so CC @IronicallySerious I guess.

[IronicallySerious]

The "Select an available VCS" refers to a GDNative object placed in the project folder that extends EditorVCSInterface. @Zylann
To use the integration you will have to extract this .zip file in your project folder.

Right now it lists all global scripts available because since the VCS integration is new, I kept things as simple as possible. I would expect the dialogue box to raise an error in the output if you selected a script that is not the Git plugin so the VCS functionality stays hidden.

I would probably fix in this line here: https://github.com/godotengine/godot/blob/24e1039eb6fe32115e8d1a62a84965e9be19a2ed/editor/plugins/version_control_editor_plugin.cpp#L384

I can get this done after Monday because of my exams, but if someone is interested they can have a look. If we are able to detect what class a GDNative plugin extends then it is a simple if statement because all VCS plugins will extend EditorVCSInterface

EDIT: Sent a PR for this.