FR: Show number of results per aggregate

The current module shows no information as to how many items are there for each available select option.

Expected behaviour:

In the filter configuration, there will be a checkbox "Show number of results". When checked, a string will be appended at the end of each option with a parentheses and the number of results.

For example, a select list:

Motorbikes
Cars
Trucks

Will turn into

Motorbikes (8)
Cars (4)
Trucks (12)