installed-page: Implement the redesign

This implements the installed page redesign found here: https://gitlab.gnome.org/Teams/Design/software-mockups/-/blob/master/adaptive/installed.png

In practice, it hides the description, make the Uninstall button turn into an icon when the sidebar is folded, and sets the clamp size to the defaults as the previous size is way too wide now.

Before

Capture_d_écran_vidéo_de_24-06-2021_12_56_10

After

Capture_d_écran_vidéo_de_24-06-2021_12_48_07

Helps: #1111 (closed)