[test] Unit Test for Listen on an In-Use Address/Port Pair

[ppenna]

Context

We should have a unit test that exercises "listening on an in-use address/port pair" error condition.

Proposed Solution

This unit test should be added to tests/tcp.rs#tcp_bad_listen

Further Considerations

• This unit test requires SO_REUSEADDR to be introduced first.

Related Issues and Pull Requests

• https://github.com/demikernel/inetstack/pull/176