Added Generics to the Contexts in the Typescript SDK models

[howlowck]

Features Added:

• Enables Generics to the Context for all types/interfaces that has a context
• The Generic has type constraint to object
• It's a non-breaking change as the generic is optional and defaults to the original object

Reason:

I would like to strongly type the AIChatMessage and other context-enabled types; however right now, I would have to redefine the type using type intersection. The more ergonomic approach is to use generics for define what context type should be for these types/interfaces.

Demo:

With the proposed change in this PR, one can set the context type like so:

type UserMsgContext = {
  messageId: string;
  userId: string;
};

type AssistantMsgContext = {
  messageId: string;
  feedback?: {
    rating: number;
    comments: string;
  };
};

type UserMessage = AIChatMessage<UserMsgContext>;
type AssistantMessage = AIChatMessage<AssistantMsgContext>;

and we can have proper typing:

Also, if the dev tries to set the context to a non-object, it will properly have a type-check error:

[anfibiacreativa]

LGTM