macOS: add descriptions for PgUp, PgDown, End, and Home keys

These keys were not being assigned a description in the KeyboardShortcut
extension. This caused problems for the macOS command pallete.

macos/Sources/Helpers/KeyboardShortcut+Extension.swift

@@ -28,6 +28,10 @@ extension KeyboardShortcut: @retroactive CustomStringConvertible {
         case .downArrow: keyString = "↓"
         case .leftArrow: keyString = "←"
         case .rightArrow: keyString = "→"
+        case .pageUp: keyString = "PgUp"
+        case .pageDown: keyString = "PgDown"
+        case .end: keyString = "End"
+        case .home: keyString = "Home"
         default:
             keyString = String(key.character.uppercased())
         }