Function to split an IP prefix into subnets (#2)

[matt-calder]

Description

This change introduces a function ip_prefix_subnets that, given an input ip_prefix and a subnet prefix_length, splits the IP prefix into subnets of the input prefix length. The functions return an array of new prefixes of the new input prefix length.

This is a new but identical PR to #23515 that I couldn't not figure out how to recover after a botched attempt to merge and squash.

This is a complimentary sister function to the ip_prefix_collapse function.

Motivation and Context

This change addresses issue 23514.

Impact

This change introduces a new user-facing function ip_prefix_subnets.

Test Plan

Unit tests

mvn clean install -Dtest=TestIpPrefixFunctions -Dmaven.javadoc.skip=true -DskipUI -T1C -fn -pl presto-main

Contributor checklist

• Please make sure your submission complies with our development, formatting, commit message, and attribution guidelines.
• PR description addresses the issue accurately and concisely. If the change is non-trivial, a GitHub Issue is referenced.
• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
• If release notes are required, they follow the release notes guidelines.
• Adequate tests were added if applicable.
• CI passed.

== RELEASE NOTES ==

General Changes
* Add function :func:`ip_prefix_subnets` that splits the input prefix into subnets the size of the new prefix length. ... :pr:`23656`

[steveburnett]

LGTM! (docs)

Pull branch, local doc build, looks good. Thanks!

[kaikalur]

We generally use all upper case for static constants