Cleanup tests

Since this started as a quick draft/prototype on the side, the tests were written super fast and need cleaning. Many tests are also missing.

List of tasks:

- [ ] Reorganize `ContextualBindings` unit tests
- [ ] Add some automated tests for `ContextualBindings.AspNetCore`
- [ ] Add some automated tests for `Modules`
- [ ] Automate the run of tests from the sample app