Add CfNoLookup

[Simn]

This adds a class field flag to mark fields as unlookupable for cases such as #11817. I've only implemented it for statics for now, but there might be other situations where we generate fields that we don't want to explicitly access.

The test I added fails on the unixes for some reason. @kLabz Any chance you could take a look at that?

[kLabz]

Uh. I can repro locally, not sure yet why that completion request fails with {"jsonrpc":"2.0","id":1,"error":{"code":0,"message":"Compiler error","data":["No completion point"]}}

[kLabz]

Oh, it's because Main.hx isn't invalidated, and file time check is not precise enough to see changes made right before. Need to invalidate or wait (or check file time with better precision, I can open a PR for that)

Works fine with runHaxeJson([], ServerMethods.Invalidate, {file: file}); before completion request.

[Simn]

Aaah right, it's always that...