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
It seems that this mode didn't get much love when I added the bubbles so
it was quite broken. This patches removes the bubbles and fix the
alignment issues when using this mode.
We probably should rename it to compact mode in a follow up commit (but
not this one so we can backport it to the stable branch).
Previously, when there was no avatar set, the source property of Avatar was still set to 'image://mxc/',
which caused Avatar to load that from the imageprovider. The imageprovider can't provide an empty image and aborts with error
