Bug
1820893 - Build nightly-as-release in CI on all desktop platfroms. r=aryx,glandium,firefox-build-system-reviewers,bhearsum,taskgraph-reviewers
This patch adds a new nightly-as-release build for Windows, Linux, and MacOSx. These are nightly builds, but built with the following additional flag: `ac_add_options --as-milestone=release`
Three new builds are also added to CI: macosx64-nightly-as-release-shippable/opt, win64-nightly-as-release-shippable/opt, and linux64-nightly-as-release-shippable/opt
These are used to make 3 test-platforms to run browsertime tests in a following patch.
Differential Revision: https://phabricator.services.mozilla.com/
D172029