Allow "str" for function arguments that accept "col" expressions #1757

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
This is an extension of #1563 and similar PRs.
I tried to write total_size = st.aggregate([], [F.sum("some_column")]) but realized I had to wrap some_column in dfn.col.

Describe the solution you'd like
I'd like functions that take a column as an argument to also accept a string so I can just pass the column name.

Describe alternatives you've considered
Wrapping it myself.

Additional context
If we update this similar to other interface generalizations we should update the doc strings to reflect this simplification.