Rework chat line templates and logic

- 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

mods/ts/mod.yaml

@@ -180,6 +180,7 @@ ChromeLayout:
 	common|chrome/missionbrowser.yaml
 	common|chrome/confirmation-dialogs.yaml
 	common|chrome/editor.yaml
+	common|chrome/text-notifications.yaml
 
 Voices:
 	ts|audio/voices.yaml