Consider `network.pause()` in `NetworkApi`

[kettanaito]

Scope

Improves an existing behavior

Compatibility

• This is a breaking change

Feature description

• More context in MSW sometimes still handles requests after worker is stopped #2597

Proposed changes

Add a .pause() method on the NetworkApi and transitively inherit it on setupWorker/setupServer APIs.

Motivation

The semantics of worker.stop() is confusing. Nothing gets stopped or unregistered. The interception gets paused and then implicitly resumed via another worker.start(). I find that utterly confusing.

Instead, the network API should encapsulate:

• .pause() to pause the interception. Performs in-flight requests as per handlers;
• .resume() to resume the interception. Passes through the in-flight requests.

Specific methods like start/stop become truly reciprocal and worker.stop() then:

• Returns a promise so it can be awaited;
• Unregisters the worker and awaits the confirmation of that;
• Cleans up internal side effects.

[kettanaito]

If we support aborting requests, the .pause() method migjt accept an option to let the user decide how to handle in-flight requests.

network.pause({ pendingRequests: 'abort' })

This might not be needed if we have something like network.abortAll(). This is open for debate and not the final proposal.