[Shader] Port VS plugin to open source editors or support it in gamestudio's text editor

Is your feature request related to a problem? Please describe.
Xenko has a hard dependency at the moment with Visual Studio as authoring IDE.
Now that Xenko is fully open source under the MIT license, it probably doesn't make sense to have a dependency on a privative IDE, so ideally Xenko should embrace open source editors as part of a more open and free engine ecosystem, and remove the dependency with closed-paid IDEs. Visual Studio Community is free-to-use, but just for individuals, teams of less than 5 people, or academic and open source projects. Rendering Xenko as a show stopper for many indie teams that could not afford paying the hefty prices of the perpetual licenses, would not like to be restricted by subscription based renting software, or would simply like to support a fully open source toolchain (blender, krita, gimp, vscode, etc).

Describe the solution you'd like
At the moment, according to @Kryptos-FR, the only hard dependency lies on the Visual Studio Plugin for authoring shader effects. So ideally that dependency could be made optional, by means of offering a manual alternative, or even better implementing as well out-of-the-box support for visual studio code which is open source, free from restrictions, and massively supported and used by the development community with hundreds of plugins and integrations.

Start by reviewing the shader authoring dependency on the Visual Studio Plugin described in the issue and the linked forum discussion. Define whether the result should be an optional manual workflow or support for Visual Studio Code or the gamestudio text editor; done means shader authoring no longer requires Visual Studio.