Add IP utils on @std/net

[Octo8080X]

Is your feature request related to a problem?

While adding a feature to Fresh, it was recommended that this functionality—being a desirable, general-purpose process for @std/net—should be addressed by creating an issue in this repository.
This process itself was ported from Hono.

Is your feature request related to a problem? Please describe.

There’s a general-purpose process that would be desirable to add to @std/net.

I’d like to add a set of utility functions.

Describe alternatives you've considered

Implementation into Fresh itself

What I mainly want to prepare is…

• Determine whether an IP is IPv4 or IPv6
• Validation process to check whether a given IP matches a specified static IP or CIDR notation.

[iuioiua]

How would you like the API look? My suggestion:

1. isIPv4(value: string): boolean
2. isIPv6(value: string): boolean
3. subnetContains(subnet: string, address: string): boolean

[Octo8080X]

@iuioiua

Thanks for the suggestion.
I think I like the third one — matchSubnet(subnet: string, address: string): boolean — but I’m not strongly attached to it.