DNR: Add filter_list_converter tool.

Filter List Converter is a tool to convert filter list files in the text format
to a JSON file in a format supported by the Declarative Net Request API. It can
either output the complete extension (with a manifest file and a JSON ruleset)
or just the JSON ruleset.

This is based on the ruleset converter module in the subresource_filter
component.

BUG=972290

Change-Id: Id67ccaa5cc3cc469da67865c3754b41182d1ab9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1139592
Auto-Submit: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Commit-Queue: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672233}
11 files changed