[TOOL IMPROVEMENT] IP Subnet Calculator - Allow conversion TO CIDR

[yurividal]

It would be cool if the tool also allowed for input as
IP and Subnet Mask

Example:
IP: 192.168.0.5
Subnet Mask: 255.255.255.0

Tool would automatically understand its a /24 and display results accordingly.

[sharevb]

Hi @yurividal, IPv4 Subnet Calculator in #969 can now handle 192.168.0.1/255.255.255.0 as input instead of /24