compute_value_frequencies - take in `modArray` parameter
compute_value_frequencies - take in `modArray` parameter

This is in preparation for an upcoming patch which will allow us to analyze
keys of a Module object whose values are arrays of strings.

Signed-off-by: Pang Yan Han <22594c345857f664c61cd411f607c4d40a9d4af9@gmail.com>

yanhan/cljs-nusmods,yanhan/cljs-nusmods,yanhan/cljs-nusmods