Need linter warning for namespace and models with the same name

In C# (and possibly other languages) having a namespace named the same as a model (whether via clientName or directly in the spec) will result in build errors. We should warn about this up front to save time and rework.

The issue names no files, tests, or entry points. Start by locating the TypeScript linter implementation and its existing diagnostic tests, then trace how namespace and model names are represented; done means a clear warning appears for the conflicting C# case, including names supplied through clientName.

Written by the indexing model from the issue text.