hide the samples related commands from flutter create #51859
Description
We should hide the sample related commands from flutter create. IDEs don't call these anymore - they instead identify samples in-line in the source code you have open, and show hyperlinks to open the hosted versions of these samples in the generated docs.
And, the samples aren't pedagogical getting started flutter apps, unlike the flutter create templates. Having both samples and templates in flutter create is esp. confusing for new users, as to which ones they should create to get started.
-s, --sample=<id> Specifies the Flutter code sample to use as the main.dart for an application. Implies --template=app. The value
should be the sample ID of the desired sample from the API documentation website (http://docs.flutter.dev). An
example can be found at https://master-api.flutter.dev/flutter/widgets/SingleChildScrollView-class.html
--list-samples=<path> Specifies a JSON output file for a listing of Flutter code samples that can created with --sample.