Api: Return information about user subscription in user resource

[EkimoCode]

The problem: the user might have canceled the subscription and the end of the period not be premium. the frontend does not know this and doesn't know where to show an "unsubscribe" or "renew subscription".

Suggested solution: add that information in the User resource (get api/User)
I would go with User.EndOfCurrentTime from subscription and User.HasCancelled a new bool property of subscription.
As we are at this point let's go to the end and share also SubscriptionStatus from

[ElSalvo96]

The renewed subscription is a new subscription. If the user is premium I don't insert anything, if the user is not premium I call stripe intent!

What type of control needs to be made in the frontend? I have just the information if the user is premium or not. We don't need anything else.

[TouchySpidey]

This PR became relevant
GenesiAI/PluginsWebPortal#137

as linked branch will be merged, user info will be as follows

public class UserInfo
{
    public bool IsPremium { get; set; }
    public DateTime? ExpireDate { get; set; }
    public bool? IsAutoRenewActive { get; set; }
    public ChatData ChatData { get; set; } = null!;
}