Code Insights: Add collapse state for the drill-down filter panel on the standalone page
Created by: vovakulikov
Follow for https://github.com/sourcegraph/sourcegraph/pull/35043
Currently we don't collapsed state for the drill-down filter panel. We should add this in order to improve the standalone page UI.
Also we don't have a separator element between different filter sections in the horizontal mode of the drill-down component's layout. We should add this, it's relatively small change so it might be a part of this issue.