explicitly enable ATS in app template (#37923)

Summary:
Pull Request resolved: #37923

Changelog: [Internal]

in this change, i'm looking to make sure our app template will not violate apple best practices and minimize probability of app rejection.

this change entails two guardrails:
- explicitly marking disabling ATS as disabled with a comment. even though this is already the case, this will make it more unlikely someone will override this
- replacing the localhost domain override with the apple provided NSAllowsLocalNetworking key, which is the recommendation

Reviewed By: sammy-SC

Differential Revision: D46707159

fbshipit-source-id: 8fe407d08767269a18fb15c80fdd83a58cf2a4a8

Author: philIip

packages/react-native/template/ios/HelloWorld/Info.plist

@@ -26,14 +26,11 @@
 	<true/>
 	<key>NSAppTransportSecurity</key>
 	<dict>
-		<key>NSExceptionDomains</key>
-		<dict>
-			<key>localhost</key>
-			<dict>
-				<key>NSExceptionAllowsInsecureHTTPLoads</key>
-				<true/>
-			</dict>
-		</dict>
+	  <!-- Do not change NSAllowsArbitraryLoads to true, or you will risk app rejection! -->
+		<key>NSAllowsArbitraryLoads</key>
+		<false/>
+		<key>NSAllowsLocalNetworking</key>
+		<true/>
 	</dict>
 	<key>NSLocationWhenInUseUsageDescription</key>
 	<string></string>