Create an independent release workflow

[seanvaleo]

• Create a release workflow that is independent of the other workflows. It should run whenever a new tag is created (usually in the github UI).
• Ensure build/test only runs once on a PR (before this it was running twice for each PR)
• Move integration tests out of the regular build/test workflow. They can be run manually (usually using the github UI). The advantages of this are:
  • Prevent integration test failures from blocking development/release (usually the failures are related to the CI environment)
  • No more waiting on integration tests for changes not related to code
  • No waiting for integration tests to run twice (on PR and then on master) which slows down the release process