Add module API for adding extra icons into the room header

[Johennes]

Context

• We want to provide the ability to add extra icons to the room header.
• The displayed icons can change based on which room is currently displayed
• All icons are to be displayed on the left part of the existing ones to avoid unwanted layout shift

Requirements

• Extend the RoomViewLifecycle to emit a room change event that can be listened to on the module's side.
• Use the <IconButton /> Compound component. for visual consistency with the room header
• Expose a store of room buttons

Store

The store should probably expose the following attribute for every button

• An SVG symbol
• And most probably the component props of the <IconButton /> however it is probably not desirable to create a direct mapping

We might also want to provide a way to open a hyperlink and use an anchor rather than a button and an onClick callback

[emmaburton1]

@Johennes Drawing your attention to the A-Timesheet-1 label. 👀

[emmaburton1]

@Johennes Do you have an ETA for when work will start on this?

Edit: Answered elsewhere, thanks.

[Johennes]

We've clarified IRL.