binding [nfc]: Clean up name of re-exported url_launcher.LaunchMode

In particular make the name appropriately specific about what's being
launched, since we're exporting it from this more general context.

Author: gnprice

lib/model/binding.dart

@@ -1,11 +1,13 @@
 import 'package:device_info_plus/device_info_plus.dart' as device_info_plus;
 import 'package:flutter/foundation.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
-export 'package:url_launcher/url_launcher.dart' show LaunchMode;
 
 import '../widgets/store.dart';
 import 'store.dart';
 
+/// Alias for [url_launcher.LaunchMode].
+typedef UrlLaunchMode = url_launcher.LaunchMode;
+
 /// A singleton service providing the app's data and use of Flutter plugins.
 ///
 /// Only one instance will be constructed in the lifetime of the app,

lib/widgets/content.dart

@@ -695,8 +695,8 @@ void _launchUrl(BuildContext context, String urlString) async {
         //   opening a URL in a browser, where the system gives the user
         //   a bit of UI to choose which browser to use:
         //     https://github.com/zulip/zulip-flutter/issues/74#issuecomment-1514040730
-        TargetPlatform.android => LaunchMode.externalApplication,
-        _ => LaunchMode.platformDefault,
+        TargetPlatform.android => UrlLaunchMode.externalApplication,
+        _ => UrlLaunchMode.platformDefault,
       },
     );
   } on PlatformException catch (e) {