LibWeb: Add pointer-events: all

This is basically the same as `auto` in the spec, so let's just treat
them as identical for now. Gets rid of some Discord CSS parser
spam. :^)

Userland/Libraries/LibWeb/CSS/StyleValue.h

@@ -264,6 +264,7 @@ enum class WhiteSpace {
 
 enum class PointerEvents {
     Auto,
+    All,
     None
 };