When a namespace gets removed from a native component, cswinrt doesn't cleanup previous generated projection.

[jlaanstra]

Describe the bug When a namespace gets removed from a WinMD of a native component, cswinrt doesn't cleanup previous generated projection. The generated C# code is still included and causes build error as the types don't exist anymore.

To Reproduce

1. Create a C++WinRT project and add a two classes in two namespaces.
2. Add a projection project that generates C# code for the native project.
3. Remove one of the classes from the native project so one namespace gets removed.
4. Build the projection project again,

Expected behavior No build errors.

Actual behavior Generated code for the removed namespace continues to be included.

Version Info 1.3.0