TeamsChannelAccount model missing aadObjectId

[tracyboehrer]

Fixes TeamsChannelAccount.add_object_id property.

The curent definition returns an additional property and a null add_object_id:

{'additional_property': {'aadObjectId': }, 'add_object_id`: None}
instead of:

{'additional_properties': {}, add_object_id }
See: https://learn.microsoft.com/en-us/dotnet/api/microsoft.bot.schema.teams.teamschannelaccount?view=botbuilder-dotnet-stable