Support netcat like behaviour for az network bastion tunnel

### Related command
az network bastion tunnel

### Extension name (the extension in question)
ssh-extension

### Description of issue (in as much detail as possible)
It would be great if the CLI would have an option to behave like netcat, read from stdin and forward to the tunnel, and read from the tunnel and write to stdout.

This would avoid hardcoding a local port which prevents any useful scripting.

It would also allow it to be used as ProxyCommand within ssh to seamlessly ssh into an azure virtual machine.

As it stands, this requires running a persistent tunnel in one window, and then ssh in another window. And it's impossible to script it in a unix environment.

And thank you for looking into this.
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