[tests] Implement serverWithStop in all test interpreters

[kciesielski]

A follow-up to #3294

Implements serverWithStop for all test interpreters, so that any server test can now be run with graceful shutdown enabled, as well as shutdown hook (called KillSwitch) available as a test parameter using testServerLogicWithStop.

Example:

   testServerLogicWithStop(
      endpoint
        .out(plainBody[String])
        .serverLogic { _ =>
          // do something with input
        },
      "Server name",
      gracefulShutdownTimeout = Some(4.seconds) // enabled
    ) { (release) => (backend, baseUri) =>
        // test body, you can use the `release: IO[Unit]` kill switch in your test 
        // to stop the server arbitrarily, or just let it be stopped by test cleanup automatically
  }

Some servers don't seem to support graceful shutdown out of the box, namely VertX, zio-http 1.x, http4s (Blaze).

[adamw]

Nice, thanks! :) one left-over type alias, I think