https improvements

[mkurz]

We fallback to https port in the play-testkit already, we need the same here. See

• https://github.com/playframework/playframework/pull/11843
• https://github.com/playframework/playframework/blob/f74c2340962b69b389e89c67a30aa474aa6a1958/transport/server/play-server/src/main/scala/play/core/server/Server.scala#L249

Also we need to construct https urls.

All this is needed for

• https://github.com/playframework/play-grpc/pull/479