Do not use flag to turn on (Namespace = namespace) feature

[JoshLove-msft]

If we are saying that Typespec namespace should correspond to csharp namespace, then this feature should not be behind a flag. It should just work that way. Otherwise, specs become very difficult to reason about as the emitter can essentially change the interpretation of what is actually a TypeSpec keyword.

[ArcturusZhang]

I think we will not add such a flag in our csharp generator.
is this issue here to notify us that we do not add this?

[JoshLove-msft]

Yes, this was opened to suggest that we not add this flag for the csharp generator. @ArcturusZhang, feel free to close this as part of your namespace implementation.