[ios] Add missing include statement (#3589)

* Add missing include

* Change files

change/@fluentui-react-native-experimental-avatar-84e79204-7c82-41ae-bcbc-731c752370f2.json

@@ -0,0 +1,7 @@
+{
+  "type": "none",
+  "comment": "Add missing include",
+  "packageName": "@fluentui-react-native/experimental-avatar",
+  "email": "araje@microsoft.com",
+  "dependentChangeType": "none"
+}

packages/experimental/Avatar/ios/FRNAvatarViewManager.m

@@ -1,3 +1,4 @@
+#import <Foundation/Foundation.h>
 #import <React/RCTViewManager.h>
 
 @import FluentUI;