Fenced frames: DisableUntrustedNetwork applies to service workers

We already get this from the partition nonce work that was done
previously. This CL adds a WPT to confirm that the partition nonce
network disabling also works for service workers created by fenced
frames. This CL also adds a WPT to test that fetch() can still be
intercepted by a service worker to serve files stored in cache after
network cutoff.


Change-Id: Id718962fcc54188f4f76d3744071e96050a70ba8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5412847


Commit-Queue: Liam Brady <lbrady@google.com>
Reviewed-by: Andrew Verge <averge@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1281942}