allow afuns to receive full alt_counts_df as optional argument

[gmbecker]

There are times when our analysis functions need access to the alt_count_df but the current optional arguments can't be used because they require. the alt_count_df to have all the variables required for row-splitting, which they often do not.

Add a new optional argument which, when present, will be passed the full un-split alt_count_df. fyi @iaugusty