feat(sql): additional sql functions

[universalmind303]

Description

Added a bunch more sql functions, and slightly refactored the existing function parsing to make it more extensible.

Notes.

I wasn't sure if there was a specific engine we are trying to mimic for the functions, or if we wanted to keep it consistent with the python methods.

For example, getting the length of a List column

engine	method
Spark SQL	size
postgres	array_length
duckdb	len | array_length | list_length
py-polars	arr.lengths

[ritchie46]

Thanks a lot @universalmind303 this is very valuable. I wanted to have full SQL front-end, but couldn't find the time. Adding all these functions is a great step in that direction.

With regard to SQL flavor. Can we mimic PostgreSQL?

We can expand later if it is needed.

[universalmind303]

With regard to SQL flavor. Can we mimic PostgreSQL?

sounds good, ill make a couple changes to more closely align with PostgreSQL