Add StatusException trailers to response metadata

[Gregory-Berkman-Imprivata]

Modified test unary request (common) - returns correct error response to check if trailers in the StatusException are propagated from server to client.
Modified ListenerDriver.scala to add the trailers from the StatusException to the response metadata

The modified test passed but other tests in MetadataSpec failed for unknown reasons

#547

[Gregory-Berkman-Imprivata]

@thesamet I modified a test to check if trailers are propagated from the server to the client. That test passed in my PR but other MetadataSpec tests started failing. I also did not modify any other request type except for unary.

[thesamet]

Looks like the change isn't compatible with Scala 2.12: https://github.com/scalapb/zio-grpc/actions/runs/5943784958/job/16119751686?pr=548#step:7:27

[Gregory-Berkman-Imprivata]

Looks like the change isn't compatible with Scala 2.12: https://github.com/scalapb/zio-grpc/actions/runs/5943784958/job/16119751686?pr=548#step:7:27

I used import scala.jdk.CollectionConverters.CollectionHasAsScala to convert the set of Keys in the metadata to scala Iterable but it has not been introduced in Scala 2.12. Switch to import scala.collection.JavaConverters._ which is deprecated in 2.13