Add package info for Crostini apps

Add package_id of owning package to the Cicerone -> Host proto
ApplicationList

BUG=chromium:822514
TEST=Apps from .desktop files associated with a package now have
'uninstall' on right-click menu; Apps from .desktop files I created do
not have 'uninstall'

Change-Id: Ibe148209763a4633a653107b2819a56146d5706f
Reviewed-on: https://chromium-review.googlesource.com/1213615


Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Ian Barkley-Yeung <iby@chromium.org>
Reviewed-by: Jeffrey Kardatzke <jkardatzke@google.com>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
Reviewed-by: Chirantan Ekbote <chirantan@chromium.org>