Adding the NetworkInterface gem

I just moved the c extentions from the metasploit-pcaprub to its own gem
pushing the gem to rubygems
arp_sweep is once again working

modified the capture mixin to use NetworkInteface instead of
pcaprub for interfaces and addresses

FIXRM #8023,#7943
now with passing msftidy
updating list_interfaces for windows, this should work?
updating the list_interfaces.rb to use the gem
fixing some copy
Fix potential nil in last_filename

Replacing #2060.  It is possible to get a nil in last_filename if
the sub! function doesn't find any 0x00s to replace, so instead
it's best to use sub(), which should at least return the original
filename.  To make sure we don't hit any other unknown conditions
that may result in nil last_filename, it's also convert with to_s
to make sure it's always a string.
Land #2085, use the new network_interface gem.
Fixes for network_interface PR #2085

Implementing the suggestions from @limhoff-r7.

See #2085

FixRM #8023
FixRM #7943
Land #2089, smb last_filename can be nil
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