Migrate from RelativeLayout to ConstraintLayout

[charlag]

RelativeLayout is de-facto deprated. It is a very slow layout (which measures children twice) and it's kinda buggy and tied to platform.
ConstraintLayout is a modern and very powerful alternative. In most cases nesting layouts is a bug with ConstraintLayout.

The most obvious case is item_status.xml. Right now it has two RelativeLayouts, ConstraintLayout and LinearLayout which is clearly too much.
It's kinda tricky to not break anything but I believe that we can simplify layout a lot.

[rkerkour]

I would like to work on this issue how I assign it?

[connyduck]

Just write here that you started working on it and send us a pull request when you are finished!