Introduce DeviceInfo as a new native module

Summary:
The `UIManager` already has a lot of responsibilities and is deeply
tied with React Native's view architecture. This diff separates out a
`DeviceInfo` native module to provide information about screen dimensions and
font scale, etc.

Reviewed By: fkgozali

Differential Revision: D4713834

fbshipit-source-id: f2ee93acf876a4221c29a8c731f5abeffbb97974

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModuleConstantsHelper.java

@@ -43,9 +43,8 @@ import static com.facebook.systrace.Systrace.TRACE_TAG_REACT_JAVA_BRIDGE;
    */
   /* package */ static Map<String, Object> createConstants(
     List<ViewManager> viewManagers,
-    boolean lazyViewManagersEnabled,
-    float fontScale) {
-    Map<String, Object> constants = UIManagerModuleConstants.getConstants(fontScale);
+    boolean lazyViewManagersEnabled) {
+    Map<String, Object> constants = UIManagerModuleConstants.getConstants();
     Map bubblingEventTypesConstants = UIManagerModuleConstants.getBubblingEventTypeConstants();
     Map directEventTypesConstants = UIManagerModuleConstants.getDirectEventTypeConstants();