feat: adds a --bind flag to allow binding the test to a specific IP address.

[panickos]

Adds the ability to provide an optional --bind <ip-address> flag to the command, which would bind the outgoing connection to a specific IP address and thus allowing the test to run through a specific network interface. This would solve the case where you would like to specifically test a wired interface vs a wireless interface connection. This is useful in enterprise environments where the wired and wireless networks could be completely separated.

Usage:
ndt7-client --bind 10.0.0.25

To test:
On a machine with 2 active network interfaces:

• Run a test with a bind on the wired interface's ip address. Verify that the traffic went through the selected interface by using tcpdump.
• Run a test with a bind to the wireless interface's ip address. Verify that the traffic went through the selected interface by using tcpdump

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This change is