Update SE examples unit tests to start the webserver using Single.await

[romain-grecourt]

SE examples have unit tests starting the server with a blocking loop:

webServer = Main.startServer();

long timeout = 2000; // 2 seconds should be enough to start the server
long now = System.currentTimeMillis();

while (!webServer.isRunning()) {
    //noinspection BusyWait
    Thread.sleep(100);
    if ((System.currentTimeMillis() - now) > timeout) {
        Assertions.fail("Failed to start webserver");
    }
}

Instead, the startServer method should be written more or less that way:

static Single<WebServer> startServer(Config config) {
    // load logging configuration
    LogConfig.configureRuntime();

    // Build server using three ports:
    // default public port, admin port, private port
    WebServer server = WebServer.builder(createRouting())
            .config(config.get("server"))
            // ...
            .build();

    Single<WebServer> webserver = server.start();

    webserver.thenAccept(ws -> {
                System.out.println(
                        "WEB server is up! http://localhost:" + ws.port());
                ws.whenShutdown().thenRun(()
                        -> System.out.println("WEB server is DOWN. Good bye!"));
            })
            .exceptionally(t -> {
                System.err.println("Startup failed: " + t.getMessage());
                t.printStackTrace(System.err);
                return null;
            });

    return webserver;
}

Then the test can do something like this:

WebServer webServer = Main.startServer(config).await();

[romain-grecourt]

This needs to be fixed for examples/media/multipart and the SE quickstart.

[romain-grecourt]

CC @tomas-langer @barchetta