Fix component type references in xplat (facebook#37903)

Summary:
Pull Request resolved: facebook#37903

The name "component" in a function type contexts will be banned in future versions of Flow (the same other keywords like typeof are today). This diff renames the offending usages in xplat files.

Changelog: [Internal]

Reviewed By: gkz

Differential Revision: D46748791

fbshipit-source-id: 0300ce24dabc7d36335354e667ec50fc1c7127cb

packages/react-native/Libraries/ReactNative/AppRegistry.js

@@ -31,7 +31,7 @@ type TaskCancelProvider = () => TaskCanceller;
 
 export type ComponentProvider = () => React$ComponentType<any>;
 export type ComponentProviderInstrumentationHook = (
-  component: ComponentProvider,
+  component_: ComponentProvider,
   scopedPerformanceLogger: IPerformanceLogger,
 ) => React$ComponentType<any>;
 export type AppConfig = {