Commit MWS backend source tree

The ASP.NET Core solution (mws.api/mws.application/mws.domain/
mws.infrastructure) existed only as untracked working files. Adding
it to version control, plus a .gitignore for build output and local
tooling directories, so the CQRS/mediator refactor plan has a real
git history to branch and diff against.

mws.application/Common/Repositories/IRepository.cs

@@ -0,0 +1,7 @@
+namespace Mws.Application.Common.Repositories;
+
+public interface IRepository<in T> where T : class
+{
+    void Add(T entity);
+    void Remove(T entity);
+}