ShaderInclude can be created in ShaderMaterial

[KoBeWi]

Tested versions

4.6 beta2

System information

W10

Issue description

When creating a shader for a ShaderMaterial, the ShaderInclude option is normally disabled.

However, if you create a ShaderInclude in FileSystem dock, the shader dialog will remember this option, so it can be selected while disabled

This creates a ShaderInclude file normally, but it's not being assigned to the material (which is expected at least).

Steps to reproduce

1. In FileSystem dock, use New Resource > ShaderInclude and create the file
2. Make a Node2D, in material property create ShaderMaterial
3. Add a shader to the material, it will show the shader creation dialog
4. The ShaderInclude will be selected despite disabled

Minimal reproduction project (MRP)

N/A

[LucaTuerk]

I'd like to take a look at this.