Search: Redirect to Current Page on Refresh

- Add search to a site's widget area and enable the overlay
- Go to a specific page or post
- Start typing a query
- See the URL replace the current page with the search query, ie `test.jetpack.com/sample-page` becomes `test.jetpack.com/?s=hello`
- While the overlay is open, refresh the page
- Exit the overlay to cancel the search
- You get redirected to the home page instead of whatever page you were visiting when you started the search.

May be an edge case and expected behavior, but could prevent any undue confusion by making sure the user stays on the page they were on when beginning the search, even if they refresh the page.

surfaced during internal testing: p8oabR-HY-p2#comment-5433

The issue names no files, tests, or entry points. Reproduce the widget overlay flow on a page or post, refresh while the search overlay is open, and compare the resulting redirect with the page where the search began. Done means exiting the refreshed overlay returns to that original page rather than the home page.

Written by the indexing model from the issue text.