[feature](function) Add jaro, jaro_winkler and jaccard_similarity string functions

[puranjay2597]

Supersedes #60799 (GitHub won't allow reopening a PR whose branch was force-pushed after it was closed).

What problem does this PR solve?

Adds 3 built-in scalar functions for fuzzy string matching and similarity scoring, useful for record deduplication, search ranking, and data quality workflows:

Function	Return type	Description
jaro(str1, str2)	DOUBLE	Jaro similarity [0.0, 1.0]
jaro_winkler(str1, str2)	DOUBLE	Jaro-Winkler similarity [0.0, 1.0] (boosts strings sharing a common prefix)
jaccard_similarity(str1, str2)	DOUBLE	Jaccard similarity [0.0, 1.0] over the sets of distinct characters of the two strings

All functions accept VARCHAR/STRING inputs, propagate NULL, and support constant folding.

Rebased and reworked since #60799

#60799 originally also proposed levenshtein and damerau_levenshtein. Both now already exist on master under different names (levenshtein via #60412, damerau_levenshtein_distance via #65278), so they've been dropped from this PR to avoid duplicating functionality — only the 3 functions above remain.

The remaining functions have been reworked from the original submission to address review feedback on #60799:

• UTF-8 support (requested by @linrrzqqq): all 3 functions now correctly handle multi-byte UTF-8 input instead of operating byte-by-byte, e.g. jaro_winkler('你好世界', '你好世间') now compares by character. Implemented with an ASCII fast path plus a UTF-8-aware path, following the exact pattern established by levenshtein/damerau_levenshtein_distance (VStringFunctions::get_utf8_char_offsets / utf8_char_equal).
• Reduced duplication (requested by @linrrzqqq): added a standalone jaro function containing the core Jaro algorithm; jaro_winkler now calls it directly instead of duplicating the matching/transposition logic.
• Jaccard algorithm clarified (requested by @linrrzqqq, who couldn't find the byte-bigram approach in Wikipedia or ClickHouse): jaccard_similarity is now a character-set Jaccard index — |A ∩ B| / |A ∪ B| over the sets of distinct bytes (ASCII) or Unicode characters (UTF-8) — matching ClickHouse's stringJaccardIndex (FunctionsStringDistance.cpp) instead of an unexplained bigram scheme. Uses a std::bitset<256> for the ASCII path per the reviewer's suggestion, and a hash set of UTF-8 characters otherwise.
• FE constant folding: added jaro/jaro_winkler/jaccard_similarity fold-constant implementations in StringArithmetic.java, matching the convention used by levenshtein/damerau_levenshtein_distance/hamming_distance.
• Input length guard: all 3 functions reject inputs over 65535 bytes with a clear error, guarding the O(m×n) Jaro matching window and the set construction in jaccard_similarity against unbounded STRING inputs.
• Expanded tests: BE unit tests (function_string_test.cpp) and regression tests now cover column-vs-column, column-vs-constant (both directions), nullable columns, UTF-8, and over-length-input error cases, in addition to the constant-only cases.

Release note

Add 3 built-in string similarity functions: jaro, jaro_winkler, jaccard_similarity.

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test

• Behavior changed:

  • No.

• Does this need documentation?

  • Yes. Will follow up with a doris-website PR, as done for Add levenshtein and hamming_distance functions #60412.

[hello-stephen]

Thank you for your contribution to Apache Doris.
Don't know what should be done next? See How to process your PR.

Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[puranjay2597]

Answering the checklist above:

1. Problem / what this adds: three new fuzzy string-matching scalar functions — jaro, jaro_winkler, jaccard_similarity. This continues [feat](func) Add levenshtein, damerau_levenshtein, jaro_winkler, jaccard_similarity built-in scalar functions #60799, whose levenshtein/damerau_levenshtein have since landed separately via Add levenshtein and hamming_distance functions #60412 and [Feature](function) Support function DAMERAU_LEVENSHTEIN_DISTANCE #65278, so those two are dropped here to avoid duplicating them.
2. Behavior changed: none — purely additive, no existing function or code path is touched.
3. Features added: see (1). jaro_winkler reuses the jaro implementation rather than duplicating it, and jaccard_similarity is a character-set Jaccard index (ASCII bitset / UTF-8 hash set) matching ClickHouse's stringJaccardIndex. All three have UTF-8 support, FE constant folding, and an input-length guard.
   4/5. Refactor / optimization: not applicable, no existing code was refactored.