Prerender2Fallback: Add `pipelineId` to Preload CDP events

Background: If Prerender2FallbackPrefetchSpecRules is enabled, Chrome
automatically triggers a prefetch ahead of prerender when a prerender
is triggered to prevent multiple fetches when the prefetch failed.
We'd like to show them in an entry in DevTools.

This CL adds `pipelineId` to CDP events `Preload.prefetchStatusUpdated`
and `Preload.prerenderStatusUpdated`. It will be used to merge
preloading attempts for prefetch/prerender that are triggered by a Spec
Rules prerender.

Frontend CL chain: http://crrev.com/c/6068033

Fixed: 342089492
Change-Id: I98cf8c30a6748dce41497544499e6e92055096a3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6055104
Auto-Submit: Ken Okada <kenoss@chromium.org>
Reviewed-by: Lingqi Chi <lingqi@chromium.org>
Commit-Queue: Lingqi Chi <lingqi@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1392055}