During a game notification duration should be the same regardless of
game speed. Switch to using wall-clock time defined in milliseconds
instead of game ticks. Also use the opportunity to rename the field
to "Duration" because "RemoveTime" is not so clear.
- Extract chat line templates and logic so they can be reused across widgets
- Make text notification styling entirely template driven (by removing chat color configuration and making color optional for `TextNotification`)
- Add a new TextNotificationsDisplay widget (based on and replacing ChatDisplayWidget)
- Add timestamp support to text notifications
