feat(duckdb): Add transpilation support for STRTOK_TO_ARRAY function

[fivetran-amrutabhimsenayachit]

Snowflake's STRTOK_TO_ARRAY(str, delim) splits a string on any character in delim (treating it as a character class), skips empty tokens, defaults to space when delimiter is omitted, and returns NULL when either argument is NULL.

DuckDB has no equivalent — a simple rename to STRING_TO_ARRAY fails because DuckDB treats the delimiter as a literal string, keeps empty tokens, errors on a missing delimiter, returns the original string for NULL delimiter, and crashes on an empty delimiter ([] is invalid regex).

[georgesittas]

@fivetran-amrutabhimsenayachit can you please rebase off of main and resolve conflicts?

[github-actions]

SQLGlot Integration Test Results

Comparing:

• this branch (sqlglot:RD-1147775-strtok-to-array, sqlglot version: RD-1147775-strtok-to-array)
• baseline (main, sqlglot version: 0.0.1.dev1)

By Dialect

dialect	main	sqlglot:RD-1147775-strtok-to-array	transitions	links
bigquery -> bigquery	24645/24650 passed (100.0%)	23495/23495 passed (100.0%)	No change	full result / delta
bigquery -> duckdb	867/1154 passed (75.1%)	0/0 passed (0.0%)	Results not found	full result / delta
duckdb -> duckdb	5823/5823 passed (100.0%)	5823/5823 passed (100.0%)	No change	full result / delta
snowflake -> duckdb	1063/1961 passed (54.2%)	0/0 passed (0.0%)	Results not found	full result / delta
snowflake -> snowflake	65133/65133 passed (100.0%)	63027/63027 passed (100.0%)	No change	full result / delta
databricks -> databricks	1370/1370 passed (100.0%)	1370/1370 passed (100.0%)	No change	full result / delta
postgres -> postgres	6042/6042 passed (100.0%)	6042/6042 passed (100.0%)	No change	full result / delta
redshift -> redshift	7101/7101 passed (100.0%)	7101/7101 passed (100.0%)	No change	full result / delta

Overall

main: 113234 total, 112044 passed (pass rate: 98.9%), sqlglot version: 0.0.1.dev1

sqlglot:RD-1147775-strtok-to-array: 106858 total, 106858 passed (pass rate: 100.0%), sqlglot version: RD-1147775-strtok-to-array

Transitions:
No change

Dialect pair changes: 0 previous results not found, 2 current results not found

✅ 36 test(s) passed