Update composer to fit in thread view

[germain-gg]

• Add the ability to not display the "reply preview" when using the composer in the thread view
• The composer assumes that there is only one instance of it in the page, it will need a bit of refactoring to make it work better when two composers are displayed in the page
• Slightly rework composer's narrow screen behaviour as the right panel is not as wide as the timeline

[germain-gg]

The VoiceRecordComposerTile component does not play very nicely with narrow screen.

After discussing with the design team it looks like we have two options, hiding the "VR" button when using that narrow mode, or making the VoiceRecordComposerTile overlay the MessageComposer when in narrow mode

We're going with the former in the short term to focus on more important value point for threads and will come back at a later stage to do the latter, tracked as part of #18806