Add a dependency on sky_tools

This is needed to make pub run sky_tools:sky_server work.
Partial fix for https://github.com/domokit/sky_engine/issues/539

packages/flutter_tools/lib/src/init.dart

@@ -144,6 +144,7 @@ name: {{projectName}}
 description: {{description}}
 dependencies:
   sky: any
+  sky_tools: any
 ''';
 
 const _libMain = r'''