Fully rename to hot restart (#17897)

* Fully rename to hot restart

Follow-up change to https://github.com/flutter/flutter/commit/f48dec570c899d8e222f5b3b7cbebd7d19fe6843

* Review feedback

packages/flutter_tools/lib/src/run_hot.dart

@@ -717,9 +717,9 @@ class HotRunner extends ResidentRunner {
     const String bold = '\u001B[0;1m';
     const String reset = '\u001B[0m';
     printStatus(
-      '$fire  To hot reload your app on the fly, press "r". To restart the app entirely, press "R".',
-      ansiAlternative: '$red$fire$bold  To hot reload your app on the fly, '
-                       'press "r". To restart the app entirely, press "R".$reset'
+      '$fire  To hot reload changes while running, press "r". To hot restart (and rebuild state), press "R".',
+      ansiAlternative: '$red$fire$bold  To hot reload changes while running, press "r",'
+                       'To hot restart (and rebuild state), press "R".$reset'
     );
     for (FlutterDevice device in flutterDevices) {
       final String dname = device.device.name;