Add support for overriding notification actor (Initiator)

[ooaklee]

SUMMARY

Currently, our system sends Discord and Slack messages using the GITHUB_ACTOR as the default initiator. This means that end users will not be tagged in the respective message when their portals are ready unless they post within an existing thread. We want to add support for users to specify the string they want to override, allowing them to pass the respective reference to tag the initiator of the given platform.

This will be accomplished by introducing the inputs notifier-discord-initiator-override and notifier-slack-initiator-override.

Current comms:

SUCCESS CRITERIA

• We need to add logic that supports both notifier-discord-initiator-override and notifier-slack-initiator-override inputs and checks if overrides are specified. Additionally, we need to leave log message(s) (debug) if using the default actor.
  • Update config tests
• Update notifier logic
• Update action.yml to to support new inputs
  • run yarn readme to update README's input section with new inputs
• Update the "getting-started" commands to include new inputs