[BP-1.17][FLINK-32706][table] Add built-in SPLIT_STRING function

[hanyuzheng7]

What is the purpose of the change

This is an implementation of SPLIT

Brief change log

Splits a string into an array of substrings based on a delimiter. If the delimiter is not found, then the original string is returned as the only element in the array. If the delimiter is empty, then all characters in the string are split. If either, string or delimiter, are NULL, then a NULL value is returned.
If the delimiter is found at the beginning or end of the string, or there are contiguous delimiters, then an empty space is added to the array.

• Syntax
  SPLIT(string, delimiter)

• Arguments
  string: The string need to be split
  delimiter: Splits a string into an array of substrings based on a delimiter

• Returns
  If the delimiter is not found, then the original string is returned as the only element in the array. If the delimiter is empty, then all characters in the string are split. If either, string or delimiter, are NULL, then a NULL value is returned.

• Examples

SELECT SPLIT('abcdefg', 'c');
Result: ['ab', 'defg']

• See also

1. ksqlDB Split function
   ksqlDB provides a scalar function named SPLIT which splits a string into an array of substrings based on a delimiter.
   Syntax: SPLIT(string, delimiter)
   For example: SPLIT('a,b,c', ',') will return ['a', 'b', 'c'].
   https://docs.ksqldb.io/en/0.8.1-ksqldb/developer-guide/ksqldb-reference/scalar-functions/#split

2. Apache Hive Split function
   Hive offers a function named split which splits a string around a specified delimiter and returns an array of strings.
   Syntax: array split(string str, string pat)
   For example: split('a,b,c', ',') will return ["a", "b", "c"].
   https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF

3. Spark SQL Split function
   Spark SQL also offers a function named split, similar to the one in Hive.
   Syntax: split(str, pattern[, limit])
   Here, limit is an optional parameter to specify the maximum length of the returned array.
   For example: split('oneAtwoBthreeC', '[ABC]', 2) will return ["one", "twoBthreeC"].
   https://spark.apache.org/docs/latest/api/sql/index.html#split

4. Presto Split function
   Presto offers a function named split which splits a string around a regular expression and returns an array of strings.
   Syntax: array split(string str, string regex)
   For example: split('a.b.c', '.') will return ["a", "b", "c"].
   https://prestodb.io/docs/current/functions/string.html

Verifying this change

This change added tests in CollectionFunctionsITCase.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• 54a0d04 Azure: SUCCESS

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[MartijnVisser]

Closing this PR since we don't backport new features into existing releases