Global namespace vs file

[timotheeguerin]

Wondering if we could make a change so that you never update the global namespace for anything but adding a namespace.

Which means if you add scopeless types to a typespec file it would still scope it to a virtual file namespace and 2 files wouldn't conflict with each other.

For example the following would have no issue

import "./b.tsp";

model A {}

// b.tsp

model A {} 

This comes up as defining Model or Operation or any types under Reflection directly at the root of a project just crash everything.