Fix layout of dialog drawers

[tomasMizera]

MMDrawerDialog now inherits MMDrawer, it is scrollable and adjusts its height based on the content height.

I replaced specialComponent done via Loader with approach that we use in other places (property alias xyz: xyzm.children), the new property is called additionalContent. This way I extracted the "boundedMessage" to a standalone component that can be used when needed.

With the additionalContent it can look like this:

but you can inject any other item to it to get something custom, like: