Improve reporting events display in chrome://safe-browsing

- Currently we print the raw proto string in the
  chrome://safe-browsing/#tab-reporting page
- Instead use the JSON serialization of the protos to display this in a
  human readable format
- Verified on a local build that the values show the JSON representation
  of the exact upload request
- Added to TODOs to clean up the legacy methods when the
  `UploadRealtimeReportingEventsUsingProto` feature is cleaned up.
- On android don't include the extra serialization libraries to keep
  target apk size increases limited
- Screenshot on desktop: https://screenshot.googleplex.com/bPVWzEsKAwNrpzu
- Screenshot on android: https://screenshot.googleplex.com/L2n4wm9ocrS4su8

Change-Id: Ie5ccb6a4932fedee0c8bbb429e98a73f7f8c1dc0
Bug: 394403142
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6922750
Reviewed-by: Nancy Xiao <nancylanxiao@google.com>
Reviewed-by: thefrog <thefrog@chromium.org>
Commit-Queue: Shanthanu Bhardwaj <xanth@google.com>
Cr-Commit-Position: refs/heads/main@{#1513330}