Add tokenizerVersion parameter to bf luis:convert #550

We are training german models and would like to specify the tokenizerVersion to be injected into the json file created by bf luis:convert. Currently it's only possible to specify this parameter manually in the json file because neither the ludown nor the bf-cli tools support adding it automatically to the json file they generate from the raw .lu file.

Related ticket about the documentation for this feauture in the luis json file: https://github.com/MicrosoftDocs/azure-docs/issues/47575