Add "Environment Setup" section within Plug-in Development

[ch0m5]

Afaik, there's currently no documentation regarding setting up an environment to make custom changes to the GDExtension, be it for personal usage or to make Pull Requests to the addon.

It would be ideal to include a section that describes the steps to perform to achieve this, as it may not be entirely intuitive for some developers or may involve tools they're not familiar with. E.g., official Godot documentation elaborates on C++ compilation tools and GDExtensions, but neither Orchestrator documentation nor Godot's make mention of CMake and its usage to create an environment to alter and build the files the GDExtension uses.

Therefore, I believe having such a section would be ideal to introduce developers to the required environment to make their own changes to the GDExtension. I found myself considerably lost trying to set the whole thing up as I was unfamiliar with CMake.

A very simple example of explaining this would be something like:

1. Fork the main branch of the Orchestrator repository and update its godot-cpp and godot-engine submodules.
2. Install SCons (as per Godot's documentation).
3. Using CMake GUI or some similar tool, generate the project's solution.
4. After altering the files as desired, build the projects within the solution (using Visual Studio or some similar tool) to obtain the .dll files and whatnot, which are to be placed alongside the .gdextension file within the project folder to test these changes.