Merge branch 'feature/559-validate-certificates' into feature/584-REUSE

.gitignore

BasicUnitTest/SecurityEventTokenTests.cs

BasicUnitTest/SenderTests.cs

DemoRunner/DemoRunner.csproj

DemoRunner/SubscriberDemo.cs

DemoRunner/appsettings.json.template

Documentation/documentation.de-DE.md

E2ETest/RejectSubmissionTest.cs

E2ETest/StraightForwardTest.cs

FitConnect/Encryption/CertificateHelper.cs

FitConnect/Encryption/FitEncryption.cs

FitConnect/FitConnect.csproj

FitConnect/FitConnectClient.cs

FitConnect/Interfaces/IFitConnectClient.cs

FitConnect/Interfaces/Subscriber/ISubscriber.cs

...onnect/Interfaces/Subscriber/ISubscriberWithSubmission.cs

FitConnect/Models/Attachment.cs

FitConnect/Models/Callback.cs

FitConnect/Models/FitConnectEnvironment.cs

FitConnect/Models/SecurityEventToken.cs