Fix plugin_ffi bindings regen command and bump ffigen (#104844)

packages/flutter_tools/templates/plugin_ffi/ffigen.yaml.tmpl

-# Run with `dart run ffigen --config ffigen.yaml`.
+# Run with `flutter pub run ffigen --config ffigen.yaml`.
 name: {{pluginDartClass}}Bindings
 description: |
   Bindings for `src/{{projectName}}.h`.
 
-  Regenerate bindings with `dart run ffigen --config ffigen.yaml`.
+  Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
 output: 'lib/{{projectName}}_bindings_generated.dart'
 headers:
   entry-points:

packages/flutter_tools/templates/plugin_ffi/lib/projectName_bindings_generated.dart.tmpl

@@ -9,7 +9,7 @@ import 'dart:ffi' as ffi;
 
 /// Bindings for `src/{{projectName}}.h`.
 ///
-/// Regenerate bindings with `dart run ffigen --config ffigen.yaml`.
+/// Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
 ///
 class {{pluginDartClass}}Bindings {
   /// Holds the symbol lookup function.
@@ -48,9 +48,9 @@ class {{pluginDartClass}}Bindings {
 
   /// A longer lived native function, which occupies the thread calling it.
   ///
-  /// Calling these kind of native functions in the main isolate will
-  /// block Dart execution and cause dropped frames in Flutter applications.
-  /// Consider calling such native functions from a separate isolate.
+  /// Do not call these kind of native functions in the main isolate. They will
+  /// block Dart execution. This will cause dropped frames in Flutter applications.
+  /// Instead, call these native functions on a separate isolate.
   int sum_long_running(
     int a,
     int b,

packages/flutter_tools/templates/plugin_shared/pubspec.yaml.tmpl

@@ -23,8 +23,8 @@ dependencies:
 
 dev_dependencies:
 {{#withFfiPluginHook}}
-  ffi: ^1.1.2
-  ffigen: ^4.1.2
+  ffi: ^1.2.1
+  ffigen: ^5.0.1
 {{/withFfiPluginHook}}
   flutter_test:
     sdk: flutter