Add a String#refang method

[postmodern]

Add a core-ext method to String which can un-defang a URI or a IP address.

• hxxps://www[.]evil[.]com/foo/bar/baz -> https://www.evil.com/foo/bar/baz
• 192[.]168[.]1[.]1 -> 192.168.1.1

This might also require putting the logic into Ronin::Support::Network::URL.refang and Ronin::Support::Network::IP.refang methods, or creating a Ronin::Support::Network::Defang module to contain the defanging/refanging logic.