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 between FB names and IG usernames and building a pipeline. 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)

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• Documented new properties (with its default value), SQL syntax, functions, or other functionality.
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• Adequate tests were added if applicable.
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Release Notes

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[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Leziak / name: Samuel Majoros (ab0205e, 30f2ede, ad92969, f4bed9e, 352e7bd, 26e9c4d, 5066a31, e918bb1, e069807, 91205dd)

[steveburnett]

LGTM! (docs)

Pull branch, local doc build, looks good.

[steveburnett]

• Please sign the Presto CLA as linked in this comment.

• Please squash merge commits.