guest_os: Add COMPONENT comment to all OWNERS files

Tooling which tries to find the owning component for a file for
e.g. automated bug filing seems to only look at the OWNERS files in
the direct ancestory of that file, it doesn't look at files included
from elsewhere in the tree. Therefore we should add our component to
everything to prevent bugs from being lost.

Bug: 1113581
Change-Id: I784dd868f54d84cc226883405250c7acaf1c0b29
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2528516
Commit-Queue: Fergus Dall <sidereal@google.com>
Commit-Queue: Daniel Ng <danielng@google.com>
Auto-Submit: Fergus Dall <sidereal@google.com>
Reviewed-by: Daniel Ng <danielng@google.com>
Cr-Commit-Position: refs/heads/master@{#825659}

chrome/browser/chromeos/camera_mic/OWNERS

 file://chrome/browser/chromeos/guest_os/OWNERS
+
+# COMPONENT: UI>Shell>Containers

chrome/browser/chromeos/usb/OWNERS

 file://chrome/browser/chromeos/guest_os/OWNERS
+
+# COMPONENT: UI>Shell>Containers

chrome/browser/resources/chromeos/crostini_installer/OWNERS

 file://chrome/browser/chromeos/guest_os/OWNERS
+
+# COMPONENT: UI>Shell>Containers

chrome/browser/resources/chromeos/crostini_upgrader/OWNERS

 file://chrome/browser/chromeos/guest_os/OWNERS
+
+# COMPONENT: UI>Shell>Containers

chrome/browser/ui/views/crostini/OWNERS

 file://chrome/browser/chromeos/guest_os/OWNERS
+
+# COMPONENT: UI>Shell>Containers

components/guest_os/OWNERS

 file://chrome/browser/chromeos/guest_os/OWNERS
+
+# COMPONENT: UI>Shell>Containers