Permit lacros logs to be visible in Chrome

Currently, Chrome permits a subset of log paths (eg. /var/log) to
be directly accessible from the browser.
This change allows us to view the new lacros logs as well.

lacros log path is now accessible from browser

Bug: 1194727
Test: Added unit-test. Also deployed to local DUT and confirmed
Change-Id: I0f682a7a0a1a747bc10992a0bdb19634607677ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3140518
Auto-Submit: Eric Lok <lokeric@google.com>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Commit-Queue: David Schinazi <dschinazi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#919542}