Upgrade Instantsearch Router

## Problem

We're getting a warning to use `react-instantsearch-router-nextjs` to better handle persisting search state across our Browse Bills/Testimony pages given our tech stack. We've also seen a number of search-related bugs crop up in our testing recently related to search state not being properly preserved and this may be a silver bullet fix. We should absolutely test out this package and see if it helps manage our search issues better.

## Success Criteria
- [ ] Add the `react-instantsearch-router-nextjs` to our search library
- [ ] Test against the recent search bugs (e.g. filters resetting in the mobile view, losing pagination status when navigating into a search result in Browse Bills and back to the Browse Bills page again, etc).

## Related Links
Package: https://www.npmjs.com/package/react-instantsearch-router-nextjs
Routing Hook: (Custom hook for search routing that we use: `useRouting.tsx`)