crash: Shorten crash-reporter project alias.

Add a .project_alias file so that crash reporter changes
can/must be prefixed with "crash: " rather than
"crash-reporter: ".

BUG=none
TEST=uploaded this change

Change-Id: Iea849873cb061650909eecdc911d8805f17bc4c5
Reviewed-on: https://chromium-review.googlesource.com/244240


Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Dan Erat <derat@chromium.org>
Tested-by: Dan Erat <derat@chromium.org>