isIP function
Checks if the string is a valid IP address (IPv4 or IPv6).
Provide version 4 or 6 to validate specifically for IPv4 or IPv6.
Example:
isIP('192.168.1.1'); // true
isIP('invalid_ip'); // false
isIP('192.168.1.1', 6); // false
Implementation
bool isIP(String str, [int? version]) => _isIP(str, version);