Ref T8726. Converts these actions to be modular. No real surprises in this change.
- Maniphest Tasks
- T8726: Modularize Herald fields and actions
- Restricted Diffusion Commit
rP8ae08a3de70b: Make "Add Subscribers" and "Remove Subscribers" Herald actions modular
- Wrote some rules.
- Migrated them forward.
- Used a bunch of these rules.