Various changes (Controller and test)

- Added RootController
- Added new methods in BaseController
- Added BaseResponse
- Changed Program structure
- Added first basic test for Program

MainProject/Models/Api/Response/BaseResponse.cs

@@ -0,0 +1,10 @@
+namespace BasicDotnetTemplate.MainProject.Models.Api.Response;
+
+public class BaseResponse
+{
+    public int Status { get; set; }
+    public string Message { get; set; }
+#nullable enable
+    public object? Data { get; set; }
+#nullable disable
+}