[Blazor] Trigger state persistence from the server

[javiercn]

• Our current APIs need to be triggered from the browser.
• There are some "scheduling" issues if we try to invoke the browser APIs from the server.

Ideally, we want to provide a RequestCircuitPause API on the Circuit that the CircuitHandler instances receive that signals the browser that it needs to start pausing the circuit.

We want the client to always be involved and drive the process in graceful pause scenarios as it needs to be able to modify the UI as needed for a proper experience. Like blocking interaction by displaying a dialog (similar to the reconnect dialog one).