Creating multiple target connections with the same client port hangs the boundary CLI

[haniffm]

Describe the bug
When using Boundary CLI to create a connections with the same client port to listen to, Boundary CLI gets unresponsive.

To Reproduce
Steps to reproduce the behavior:

1. Run boundary authenticate ...
2. Run boundary connect ... -listen-port 2222. You should get a "Proxy listening information" output.
3. In a different terminal, run boundary connect ... -listen-port 2222 (notice the same port). This time you don't get any output, and the CLI get unresponsive. You can't even CTRL+C out of it. I have to do kill -9 on the last connection.

Expected behavior
I would expect that the boundary CLI would give an error message on that the port is already occupied and exit with non-zero.

Additional context
This happens often when a default client port is configured and the user is not sure that a connection is already establish.