Abstract common workflow components in regression checking.

[adithyaov]

trafficstars

We can then use worflow_call event to trigger the workflow accordingly. See: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#onworkflow_call

See this for conditional execution: https://docs.github.com/en/actions/learn-github-actions/contexts#about-contexts-and-expressions