fix: avoid duplicate IP addresses

[PsypherPunk]

As mentioned in the linked issue, if an IP appears twice (either duplicated directly or part of an overlapping CIDR), it's scanned multiple times and any open ports appear duplicated.

You can quickly see this via:

rustscan --addresses 127.0.0.1,127.0.0.1 --scripts none

This proposed change loads everything into a BTreeSet before converting it back into a Vec which:

• drops duplicates
• maintains the original order (I think) doesn't maintain the original order, just the naturally-sorted order which match existing tests (is the original order important?)

fixes #651

[bee-san]

maintains the original order (I think) doesn't maintain the original order, just the naturally-sorted order which match existing tests (is the original order important?)

Great question!! I think it should be important, but if current tests fail against that then we should fix it later on. I think if I entered a list of IPs I would want them to be scanned in that order 🤔