Hide obsolete bridges in a collapsible archive part of the bridge page

It would help make the status of obsolete bridges clearer if they were hidden behind an extra action such as uncollapsing a drawer.

Start by locating the bridge page and the code that renders obsolete bridges. Check how existing collapsible drawers or archive sections are implemented in the site, then verify that obsolete bridges are hidden initially and revealed through an extra action.

Written by the indexing model from the issue text.