Add "chunking" for database and dataframe pulls

[ericpan64]

Problem

Large memory usage could be a problem (think 1m+ rows)

Requested feature

Make it easy to pull small chunks at a time, then drop memory after a chunk is used

Alternatives considered

Additional context

• Would be good time to add in dataframes module too (i.e. apply in chunks, or something like that -- a chunking iter)
  • NOTE: Polars might already do something like this under the hood, so for dataframes, maybe just rely more on lazy execution expressions