* Make `formattedCaption in `TimelineItemEventContentWithAttachment` a `Charsequence?`, parse the formatted caption body as we do for text message bodies
* Add `TimelineItem.isWholeContentClickable` property to decide whether the click action should be triggered at the message bubble level or when some internal content is tapped instead.
* Display the formatted/linkified captions in image and video timeline item views
* Apply the `onClick` callback to the whole message bubble or only the content of the timeline item depending on `TimelineItem.isWholeContentClickable`.