The aim here is to tidy up the reply component and make it so it sizes automatically without any need to manually set widths or heights. This is achieved by putting the layout in a grid layout. The implicitwidth and height variables are also simplified meaning that the margins are no longer prone to being slightly off because the calculation didn't add up the margins and spacing right.
Also added here is a mime component which is used to provide a nicer representation for files, videos and audio in the reply because trying to put the full component in wouldn't look good.
This also fixes the situation in right to left mode where the layout now mirror properly and everything sits where it should.
New reply elements
Uses Matrix's preview API to generate embedded link previews.
Only title and description for now.
Tells the user that the message could not be decrypted because the key
was not shared with the device. At the moment, this is technically not
completely correct, but it will be when libQuotient supports reading
encrypted messages
