[cli][gradle] filter deprecated generators by default when listing available generators

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• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\. If contributing template-only or documentation-only changes which will change sample output, be sure to build the project first.
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Description of the PR

Allow users to specify a stability type to include when listing generator. Excludes deprecated generators by default.

Example output when using this new option:

$ openapi-generator.local list --include deprecated,beta
The following generators are available:

CLIENT generators:
    - csharp-dotnet2 (deprecated)
    - scala-httpclient-deprecated (deprecated)
    - swift2-deprecated (deprecated)
    - swift3-deprecated (deprecated)


SERVER generators:
    - nodejs-express-server (beta)
    - nodejs-server-deprecated (deprecated)

This also adds the experimental enum to a couple of generators which were missing it.

cc @OpenAPITools/generator-core-team