It turns out that workflows were the wrong way to abstract reusable
pieces of work. This turns common steps into custom actions (build
docs, build packager, test packager) which can be used as encapsulated
steps in multiple workflows.
This is a much more natural way to avoid duplication compared to the
previous approach of triggering one workflow from another. This also
has the benefit of all of the steps of a release being represented on
GitHub as a single workflow, making it easier to understand what is
happening and what event triggered those steps.
Change-Id: Ife156d60069a39594c7b3bb3bc32080e6453b544
a2e07a901e