Sunset the value namespace (#1720)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1720

X-link: https://github.com/facebook/react-native/pull/46930

This is not really needed anymore, we can just use `StyleLength` statics instead

Changelog: [Internal]

Reviewed By: NickGerleman

Differential Revision: D63922280

fbshipit-source-id: cd953bae8e9f68574463eafc49c33c2e85ac1856

yoga/node/Node.cpp

@@ -288,9 +288,10 @@ Style::Length Node::processFlexBasis() const {
     return flexBasis;
   }
   if (style_.flex().isDefined() && style_.flex().unwrap() > 0.0f) {
-    return config_->useWebDefaults() ? value::ofAuto() : value::points(0);
+    return config_->useWebDefaults() ? StyleLength::ofAuto()
+                                     : StyleLength::points(0);
   }
-  return value::ofAuto();
+  return StyleLength::ofAuto();
 }
 
 FloatOptional Node::resolveFlexBasis(