Workspace overview refinement and UI changes

[maria-komarova]

• Workspace thumbnails have hover, pressed, and selected states
• Workspace preview render has a corner radius @radius_s while the outer corner of the workspace thumbnail is @radius_s + 6. Those corner radii shouldn't be impacted by the style change (rounded, slightly rounded, square)
• Spacing for workspace thumbnails should be aligned to the latest mockups in Figma.
• Window previews in the overview: window titles are above the window preview, the window title shrink to the app icon when the widow previews get too small to fit the window titles copy.

Some of the changes could be covered by the #107