Amanda Tarafa Mas

feat[Spanner]: Add directed reads sample

2

Tests won't pass until https://github.com/googleapis/google-cloud-dotnet/pull/12164 is merged and release. I'm currently running them locally.

Log [here](https://source.cloud.google.com/results/invocations/778557d3-7adf-4b9c-8bff-fd3227a719c5/log) ``` Failed ComposeObjectTest.ComposeObject [611 ms] Error Message: Google.GoogleApiException : The service storage has thrown an exception. HttpStatusCode is BadRequest. Cannot compose object with destination storage class COLDLINE from...

Kokoro has made some changes which mean we are now running on a Kokoro owned VM with Kokoro owned credentials that don't have access to our testing project.

https://github.com/GoogleCloudPlatform/dotnet-docs-samples/tree/flex-dotnet3-and-earlier

Changes in this PR will be published to Nuget on the next release cycle.