feat: Add an example for dotnet

[CaptainStandby]

This adds a basic example on how to make use of Ory Network in an ASP.NET application.

Checklist

• [x] I have read the contributing guidelines and signed the CLA.
• [ ] I have referenced an issue containing the design document if my change introduces a new feature.
• [x] I have read the security policy.
• [x] I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security vulnerability, I confirm that I got approval (please contact security@ory.sh) from the maintainers to push the changes.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [x] I have added the necessary documentation within the code base (if appropriate).

[CaptainStandby]

I have made the following changes:

• reworked the example, so it doesn't contain all those nasty generated files from dotnet new mvc
• fixed line endings and file encodings
• fixed license headers
• added docker support and e2e test
• added ci workflow to run the e2e test

I will have to take a look at why the django-ory-cloud workflow fails