feat(client): `ephemeral-ports-range` for client

We already added this option for proxy (in !102 (merged)), which is usually utilized to make the proxy NAT type unrestricted. I think there should be the same option for clients that are willing to set up port forwarding. Becoming an "unrestricted" client gives you access to more proxies, which makes it more likely that you are not gonna get paired with a proxy that is blocked by IP, especially that there are not that many unrestricted proxies, at least right now (~2500 inuqie IPs, to be precise, see https://snowflake-broker.torproject.net/metrics, snowflake-ips-nat-unrestricted).

After that, writing instructions somewhere would be nice too.

Somewhat of an alternative (or just a complementary thing) is UPnP (and alike): #40317