Create a new GoToTypeDefinition endpoint

[jtschuster]

Creates a new endpoint to go the definition of the type of a local variable, parameter, field, or property. The implementation borrows heavily from the GotoDefinition endpoint. Fixes issue #2297

This endpoint should be helpful in C# workflow, especially when using implicitly typed variables that don't have the name of the type anywhere in the file. This also provides an endpoint to use with the VS Code command editor.action.goToTypeDefinition.

Example:
file1.cs:

class C {
    C NamedConstructor() { return new C(); }
}

file2.cs:

class D {
    void method() 
    {
        var variableName = NamedConstructor();
    }
}

GoToTypeDefinition at the position of variableName would return the definition of the class C in file1.cs.

[jtschuster]

@filipw @JoeRobich You seem to be the most active in this repository, could you take a look or let me know if there's anything I need to do for a PR?

[JoeRobich]

@filipw @JoeRobich You seem to be the most active in this repository, could you take a look or let me know if there's anything I need to do for a PR?

I will take a look at this next week.

[jtschuster]

@JoeRobich Just checking back in. No rush, just don't want this to get lost.

[JoeRobich]

Thanks for the contribution!

[JoeRobich]

@filipw Since this is the first iteration of this endpoint, is it ok to be under V2?

[filipw]

I think it should just be /gototypedefinition, we do not version at API level but on endpoint level.
for example /completion is the modern version of intellisense and it was not versioned as v2

[jtschuster]

Okay, it's updated accordingly

[filipw]

I think this should use ExternalSourceServiceFactory to also cover cases when decompilation is enabled

[JoeRobich]

This file seems to be mostly a cut and paste of the GotoDefinitionV2Handler. Perhaps we can update all the Navigation handlers as a follow up.

[jtschuster]

This file seems to be mostly a cut and paste of the GotoDefinitionV2Handler.

Yeah, it was a copy and paste. I've updated to use the ExternalSourceServiceFactory.

[filipw]

I am not sure you can assume that metadata will be used, because the user might have enabled decompilation

[jtschuster]

Thanks for the tip, I've updated to use the IExternalSourceService from the ExternalSourceServiceFactory.

[JoeRobich]

Thanks @jtschuster!

[filipw]

thanks!