* ci: Add mock build alternative for fast testing
* ci: Always cache build
* ci: Extract steps to download build stage artifacts
* ci: Add template to release to GitHub
* ci: Add template to release to Azure Universal Artifacts
* ci: Split mainline to two pipelines
Identified a bug in the script which uses the azure image when attempting to upgrade python3-pip.
Package index was out of date because apt-get update was not ran before attempting the upgrade.
