fix definition handler for external dtos and enums

[bryankenote]

Based on how the extern keyword works (FacilityApi/Facility#41 (comment)):

... it's sort of like a C extern. Facility does not resolve the type when generating source files. It trusts that what you put in as an extern type will exist. It's up to the project to ensure the specified types exist at build time.

It may not make sense to jump to another fsd file, which is what I originally hoped to accomplish. However, the definition handler should still at least jump to the definition with the extern keyword within the current file.

This is a simple fix, the language server is just resolving the name of the member with some internal code that was never updated after the extern keyword was added to the parser.

[ddunkin]

Testing this out in VS Code, I a "no definition found" error.

Does it work for you and I'm not testing it right?

[bryankenote]

https://recordit.co/FuBGvvn4tB
Working for me. I am testing with https://git.faithlife.dev/Logos/AcademicServices/blob/master/fsd/AcademicServices.AcademicApi.v1.fsd

Did you miss any of these steps?

1. build the language server
2. uncomment https://github.com/FacilityApi/FacilityVSCode/blob/57667c7a720b63b6661da58e8db3733434d8cba7/src/extension.ts#L9-L19
3. build the extension
4. debug the extension

[ddunkin]

I figured out what I was doing wrong.