useSearchParams support without Suspense boundary

[KraKeN-47]

Prerequisites

This thread was started because of answers coming from #70574. There's no clear answer if/how shallow searchParams are/can be supported without the <Suspense> wrapper.

Goals

1. Allow for CSR listening on searchparams changes and state retrieval.
2. Prevent unnecessary streaming when checking for exclusive client-side searchParams.
3. When unnecessary streaming is prevented - SSR performance should be improved by default.

Non-Goals

No response

Background

In the app router it is currently not possible to listen for query parameters purely on the client-side without opting in to Suspense.
However history.pushState and history.replaceState are supported for CSR shallow routing.
I believe the same support should be introduced for the client-side search parameters tracking via useSearchParams hook as it is currently exclusively allowed to be used inside a <Suspense> wrapper. As Suspense opts into streaming. Unnecessary streaming is a performance bottleneck for the things you want to do exclusively on the client-side only, for example: e-commerce product lists, CSR filtering, manipulating UI client-side state which is completely unrelated to RSC's.

Proposal

• Expose a shallow option for useSearchParams that would enable to subscribe to search params changes (router.push should be included) on the client-side without needing the use of a <Suspense> wrapper.
• Expose additional router event that would indicate that a push was made (should be compatible with shallow routing otherwise)
• If it is possible to listen to searchParams via native browser api somehow, docs improvements would solve this issue (with respect of next router)