MessagingClient dies and connection won't be reopen

I'm currently using the `MessagingClient` to send c2d messages over the iothub. We're sometimes experiencing the problem of losing the connection to the IoTHub.

We're using spring-boot with Kotlin and made a `Bean` which we're using internally.

`java.util.concurrent.TimeoutException: Timed out waiting for the connection to the service to open` is the error we're experiencing.

We already had a `try-catch` around the `sendAsync` method which tried after an exception occurred to call it like this:
```kotlin
private fun reopenConnection() {
try {
messagingClient.close()
} catch (ex: Exception) {
log.error("Failed to close IoT Hub connection", ex)
}

try {
messagingClient.open(reconnectTimeoutMs)
} catch (ex: Exception) {
log.error("Error reopening connection to IoT Hub", ex)
}
}
```

The closing did work and the `open`-call failed with the given exception message above. After that, the `open` call will never fail again or at least doesn't show that it didn't work.

I would expect that this works without any problem. The timeout is kinda low currently configured 10 seconds. But we will call this reopen in exceptional cases which occur during `sendAsync`:

```kotlin
suspend fun sendMessage(deviceId: String, message: Message) {
try {
messagingClient.sendAsync(deviceId, message, {
when (it.wasSentSuccessfully()) {
true -> {
// ...
}

false -> {
// ...
}
}
}, "sendTelemetryEvent")
} catch (ex: Exception) {
// ...
reopenConnection()
}
}
```

We now adjusted the given `reopenConnection` function to use a `Semaphore` to avoid multiple calls:
```kotlin
private suspend fun reopenConnection() {
semaphore.withPermit {
try {
messagingClient.open(reconnectTimeoutMs)
} catch (ex: Exception) {
log.error("Error reopening connection to IoT Hub", ex)
}
}
}
```
Which still seems to break it. Some feedback regarding this would be great what do we need to change to make it work (besides increasing the timeout)