Create a global default asn.DefaultClient

[Mzack9999]

Description

The package asn/asn.go should contain a DefaultClient and global helper functions using this default client. Similarly to net/http and projectdiscovery/gologger:

DefaultClient = New()
...
func GetCIDRsForASNNum(value string) ([]*net.IPNet, error) { ... }
func GetIPAddressesAsStream(value string) (chan string, error) { ... }