bindings: Rename dotnet project to UnicornEngine

Add a few more properties to prepare a nuget package

bindings/dotnet/UnicornEngine/UnicornEngineException.fs

@@ -0,0 +1,9 @@
+namespace UnicornEngine
+
+open System
+
+type UnicornEngineException(errNo: Int32, msg: String) =
+    inherit ApplicationException(msg)
+
+    member this.ErrorNo = errNo
+