searching binary matches "not indexed reason" from zoekt

Created by: keegancsmith

When skipping a file, we include the skip reason in the file contents: https://github.com/sourcegraph/zoekt/blob/48642cac2d971e23f6102e54d42957786c779f22/indexbuilder.go#L392

Binary files have the SkipReason: binary content at byte offset %d.