aconfig: dump --filter: hook up command line args to dump.rs

This is the first step towards teaching dump to (optionally) filter
which flags to print.

A follow-up CL will implement dump::create_filter_predicate.

Bug: 315487153
Test: atest aconfig.test
Change-Id: Ibe0d4ce6563d3b5718fedd3ebfd45fbf5d935b92