Make RST: Exclude godot-cpp test project files

[aaronfranke]

This is required to avoid erroring in the case of multiple third-party modules that can build as both GDExtension and engine modules while those modules also have godot-cpp cloned inside of them. Without this PR, make_rst.py will give an error about duplicate classes from the multiple godot-cpp test projects.

ERROR: modules/1d/addons/nd/src/godot-cpp/test/doc_classes/Example.xml: Duplicate class "Example".
ERROR: modules/2pt5d/addons/2pt5d/src/godot-cpp/test/doc_classes/Example.xml: Duplicate class "Example".
ERROR: modules/4d/addons/nd/src/godot-cpp/test/doc_classes/Example.xml: Duplicate class "Example".
ERROR: modules/nd/addons/nd/src/godot-cpp/test/doc_classes/Example.xml: Duplicate class "Example".

I know this is a niche thing, but it would be nice to have the script working and CI passing in this case.

[dsnopek]

Will this work even if the "godot-cpp" directory isn't at the top level?

I know most projects put it there, but I've got a couple that put it under "thirdparty" and other folks may do other things as well. Maybe we need a way to provide a list of exclude directories?

[aaronfranke]

Yes, in fact that's how I use it. This is just a string match, it will work regardless of how deep it is.

[Calinou]

Do paths returned by os.walk() on Windows use forward slashes? If not, this check won't work on Windows.

[akien-mga]

I'm not fond of hardcoding something specific to a thirdparty repository here.
A project might use godot-cpp but with a different folder name (e.g. it may be cloned as godot-cpp.git), and the test folder may not always be there in the future or include documentation.

I think this would be better solved by improving the logic so it doesn't go so deep.

The patterns to support are:

modules/<name>/doc_classes
platform/<name>/doc_classes

So if we limit ourselves to one level of depth it should be fine I expect.

Otherwise, adding a way to pass excludes from the command line might be better than hardcoding exceptions here.

[aaronfranke]

@akien-mga In my module I am using modules/4d/addons/4d/doc_classes. Thoufh it is possible to infer the maximum depth level if we read the modules config.py files, that would be a larger change than I originally intended.

[dsnopek]

This looks good to me!