Backport CAMEL-13399

ZipAggregationStrategy exponentially slow down with the increase of files aggregated because recreate the zip from each new files to include.
The issue has been fixed in the Camel 3 CAMEL-13399.

A tested workaround is to backport the Camel 3 implementation on Camel 2 as customer aggregator. Another, not tested, workaround could be to collect all filenames with a custom aggregator and implements a processor that zips them all right after.