Automatically add Incident timeline event when a certain event occurs

We need to automatically create Incident Timeline when a certain event occurs.

We have some options for doing this discussed in #344057 (comment 725505698), (manually (via explicit call in code) creating vs automatically)

Requirements

• Automatically created timeline events should not be able to be edited.
• Automatically created timeline events should not have a corresponding system note.
• MVC
  • When an Incident is opened and by whom
  • When an Incident is closed and by whom
  • Alert status updated and by whom
  • Incident status updated and by whom

Which events?

Existing System Note	Alert/Incident	Sync to timeline?
TODO	TODO	TODO