GitLab

Updating App Remoting build files to include an OAuth2 client ID and manifest key which we will set in the manifest at build time.  This removes the need to run any scripts before uploading to the webstore.

Chromoting updates will be handled in a subsequent change (TODO added).

Also made a few changes to handle the new prod_testing environment.

BUG=

Review URL: https://codereview.chromium.org/1062963002

Cr-Commit-Position: refs/heads/master@{#324067}