Implement metrics collection.

[whizzzkid]

Metrics cannot be collected from the service worker, it happens in the window context only for now.

Tasks

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1. Implement minimal API to send metrics to countly using fetch in serviceWorker context.
2. Collect URLs intercepted and served using the routes.
3. refactor frontend pages to utilize this common channel to push metrics.
4. Revert feat(telemetry): Refactor Metrics Tracking from background service_worker #1172

[whizzzkid]

Completed in #1242