Add missing kendo.chat namespace in API section and update typescript definitions accordingly

[Iankodj]

Bug report

The function kendo.chat.registerTemplate as mentioned here: https://docs.telerik.com/kendo-ui/controls/conversational-ui/chat/chat-items#custom-templates is missing in API Reference and the Typescript Definitions.

Also, update API to include its relation to message.type: https://docs.telerik.com/kendo-ui/api/javascript/ui/chat/methods/rendermessage

Reproduction of the problem

TS def does not include the kendo.chat namespace with its methods.

Expected/desired behavior

kendo.chat to be available in the TS defs.