feat(xanthous): Add a command to describe an item in the inventory

Add a new DescribeInventory command, bound to I, to prompt for an item
in the inventory (anywhere in the inventory, including wielded) and
display a (new) panel describing it in detail. This description includes
the description, the long description, and the item's physical
properties (volume, density, and weight).

Change-Id: Idc1a05ab16b4514728d42aa6b520f93bea807c07
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3227
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

users/grfn/xanthous/src/Xanthous/Game/Draw.hs

@@ -116,6 +116,7 @@ drawPanel game panel
   . viewport (Resource.Panel panel) Vertical
   . case panel of
       InventoryPanel -> drawInventoryPanel
+      ItemDescriptionPanel desc -> const $ txtWrap desc
   $ game
 
 drawCharacterInfo :: Character -> Widget ResourceName