Add longest_common_prefix implementation, documentation and tests

[Leziak]

Description

Add longest_common_prefix function

Motivation and Context

Feature requested by myself (😃) - I'm currently doing some data analysis at Meta which involves numerous string comparisons (i.e. string similarity). I found the levenshtein_distance built-in function really useful for this, and found that there was also a hamming_distance function. For the purposes of my data analysis, I need functions for finding out the longest common prefix, substring, suffix and ideally also the Jaro-Winkler distance. For posterity, I thought it would be really handy to have this implemented just like Levenshtein distance or the Hamming distance. So I went for it - this diff specifically contains the longest common prefix function, plus tests.

Impact

Added a longest_common_prefix function

Test Plan

Tested manually on TCPH catalog via presto-cli, then wrote tests which include non-ASCII characters (took direction from the Levenshtein distance function tests on this)

Contributor checklist

• Please make sure your submission complies with our contributing guide, in particular code style and commit standards.
• 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

Please follow release notes guidelines and fill in the release notes below.

[Leziak]

This is a carbon copy of #24651, just squashed into one commit - I decided to redo the entire pull request because of a fubar situation with my local branch, sorry for the inconvenience!

[steveburnett]

LGTM! (docs)

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

[Leziak]

How do I merge this PR? I don't see any such option despite the changes being approved and the tests passing...

[steveburnett]

Merging based on an approving committer review, and my approving doc review.