Update "no devices" text to suggest "flutter emulators"

packages/flutter_tools/lib/src/commands/devices.dart

@@ -32,7 +32,8 @@ class DevicesCommand extends FlutterCommand {
     if (devices.isEmpty) {
       printStatus(
         'No devices detected.\n\n'
-        'If you expected your device to be detected, please run "flutter doctor" to diagnose\n'
+        "Run 'flutter emulators' to list and start any available device emulators.\n\n"
+        'Or, if you expected your device to be detected, please run "flutter doctor" to diagnose\n'
         'potential issues, or visit https://flutter.io/setup/ for troubleshooting tips.');
       final List<String> diagnostics = await deviceManager.getDeviceDiagnostics();
       if (diagnostics.isNotEmpty) {

packages/flutter_tools/lib/src/commands/run.dart

@@ -216,7 +216,7 @@ class RunCommand extends RunCommandBase {
     if (getCurrentHostPlatform() == HostPlatform.darwin_x64 &&
         xcode.isInstalledAndMeetsVersionCheck) {
       printStatus('');
-      printStatus('To run on a simulator, launch it first: open -a Simulator.app');
+      printStatus("Run 'flutter emulators' to list and start any available device emulators.");
       printStatus('');
       printStatus('If you expected your device to be detected, please run "flutter doctor" to diagnose');
       printStatus('potential issues, or visit https://flutter.io/setup/ for troubleshooting tips.');