[Feature Request] --contact-address with multiple workers at specific port range.

#### Is your feature request related to a problem? Please describe.

I'm running dash worker in a isolated network A. These workers has an internal IP address (192.168.0.1) and an external IP address 10.0.0.1. There are some other workers in network B or C, they can only communicat using external address(There are firewalls or other restrictions etc.). So --contact-address. is required.
I want to run multuple workers using --nworkers > 1 ( or --nworkers auto), But:

if --nworkers is specificted, --bind-address is NOT allowed.
If --contact-address is specificted --bind-address is required.
Even though I can run multiple instances with --nworkers 1, but If I want to start hunders of worekrs in one node, thing is going to be difficult. Put another way: things could have been very simple.

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#### Describe the solution you'd like

--bind-address can specific address and a range of ports. So it no longer conflicts with --nworkers.
for example: tcp://192.168.0.1:6000-6256