Adds a new release-partner-repack-bouncer-sub-firefox task to add the partner products. This is forked from the main bouncer submission because it diverges sufficiently that this is a cleaner approach. The get_partners_to_be_published helper is used by aliases too.
Depends on D34950
Differential Revision: https://phabricator.services.mozilla.com/D35481
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extra : moz-landing-system : lando