Rename React.js entrypoint to ReactClient.js

The server entrypoint no longer depends on this module. It's now only
imported by the client. I've updated the name to reflect that it's
client-only, and can include client-only features.

packages/react/index.classic.fb.js

@@ -58,5 +58,5 @@ export {
   useSyncExternalStore,
   useTransition,
   version,
-} from './src/React';
+} from './src/ReactClient';
 export {jsx, jsxs, jsxDEV} from './src/jsx/ReactJSX';

packages/react/index.experimental.js

@@ -57,9 +57,9 @@ export {
   useSyncExternalStore,
   useTransition,
   version,
-} from './src/React';
+} from './src/ReactClient';
 
-import {useOptimistic} from './src/React';
+import {useOptimistic} from './src/ReactClient';
 
 export function experimental_useOptimistic<S, A>(
   passthrough: S,

packages/react/index.js

@@ -80,4 +80,4 @@ export {
   useState,
   useTransition,
   version,
-} from './src/React';
+} from './src/ReactClient';

packages/react/index.modern.fb.js

@@ -56,5 +56,5 @@ export {
   useSyncExternalStore,
   useTransition,
   version,
-} from './src/React';
+} from './src/ReactClient';
 export {jsx, jsxs, jsxDEV} from './src/jsx/ReactJSX';

packages/react/index.stable.js

@@ -47,4 +47,4 @@ export {
   useSyncExternalStore,
   useTransition,
   version,
-} from './src/React';
+} from './src/ReactClient';