Expose additional regexp functions

[timsaucer]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Once apache/datafusion#11946 is complete, add these functions to the python wrapper

Describe the solution you'd like

Expose additional regexp functions in python.

• regexp_count()
• regexp_instr()
• regexp_matches()
• regexp_split_to_array()
• regexp_split_to_table()
• regexp_substr()

Describe alternatives you've considered

You can work around these with existing functions.

[nirnayroy]

take