It seems that the method used to create the Teams Chat Bot is now defunct, LUIS AI Services being replaced/subsumed into Azure AI Language Services, which means that Moodle Documentation relating to the Teams Chat Bot is now also defunct.
I have created a GitHub Issue [here] discussing this issue and detailing where documentation needs to be reviewed/updated, including Moodle Documents.
As it stands, Teams Chat Bots cannot be created using existing guides. That's a weekend I'm not getting back.
Hopefully this can be fixed up soon.
David.