version contexts feedback: include warning when URL changes context

Created by: attfarhan

Add a warning on the search results page when the URL changes the version context. After being displayed once, on future searches/page loads, it should not be displayed.

We could only show the warning by adding a query param (e.g. from-toggle) when we change version contexts via the dropdown menu. When we see the query param, we don't show the warning ever. If we don't, and the context changes, we will show it.