FR: add --detach flag

[szab100]

I like this plugin, but would be nice to have a --detach / -d flag that would detach / go background once the (initial) port-forward channel has been established. My current workaround is launching it with &, followed by a sleep 5 before I let my script continue with commands trying to connect to the service to avoid connection refused..

In general, this is OK, while usually the connection becomes ready much before the 5s wait.. But sometimes, when the system is slow, it can take longer, so it would be great to get this feature instead & let it go to background once it's ready (with some configurable timeout).