layouts: Replace altline with special-2 and wide with special-3

to use the same name for the same button-style.

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/685>

data/keyboards/number/us_wide.yaml

@@ -1,8 +1,8 @@
 ---
 outlines:
     default:   { width: 37.46,  height: 42 }
-    altline:   { width: 48.39,  height: 42 }
-    wide:      { width: 88.98,  height: 42 }
+    special-2: { width: 48.39,  height: 42 }
+    special-3: { width: 88.98,  height: 42 }
     spaceline: { width: 120.58, height: 42 }
 
 views:
@@ -14,13 +14,13 @@ views:
 
 buttons:
     BackSpace:
-        outline: "altline"
+        outline: "special-2"
         icon: "edit-clear-symbolic"
         action: "erase"
     space:
         outline: "spaceline"
         text: " "
     Return:
-        outline: "wide"
+        outline: "special-3"
         icon: "key-enter"
         keysym: "Return"