DiagnosticObserver does not use null connection (dotnetcore#845)

* DiagnosticObserver does not use null connection

* Make TryGetSqlConnection static.

Co-authored-by: Dave Smith <dave.smith@ventivtech.com>

Fix memory leak when using transction to publish message. (dotnetcore…

…#816)

Fix attribute in Quick Start (dotnetcore#802)

Change from `FromService` to `FromServices`.
Ref:
https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.mvc.fromservicesattribute

Remove test connection string from sample

Add support for custom message id. dotnetcore#668

Fix browser language detection. dotnetcore#631

upgrade Confluent.Kafka to 1.4.3

Fix rabbitmq connection may be reused when close forced. dotnetcore#533

Fix diagnostics event error. dotnetcore#504

Try to fix azure service bus header cast exception. dotnetcore#483