Created & updated time stamps

Is your feature request related to a problem? Please describe. n/a

Describe the solution you’d like

• When a document is created mark the current time as DateTime.UtcNow
• When a document is modified mark the last updated time as DateTime.UtcNow

Describe alternatives you’ve considered This can be controlled manually by a user but it may be a nice addition for this library to handle.

Additional context This is what the Item class could look like

    public abstract class Item : IItem
    {        
        [JsonProperty("id")]
        public string Id { get; set; } = Guid.NewGuid().ToString();

        [JsonProperty("type")]
        public string Type { get; set; }

        string IItem.PartitionKey => GetPartitionKeyValue();

        public Item() => Type = GetType().Name;

        protected virtual string GetPartitionKeyValue() => Id;
        
        [JsonProperty("createdUtc")]
        public DateTime CreatedUtc { get; internal set; }

        [JsonProperty("lastUpdatedUtc")]
        public DateTime LastUpdatedUtc { get; internal set; }
    }

[IEvangelist]

I like the idea of a readonly member that reads, parses and represents the LatestUpdatedUtc. 👍🏼

[mumby0168]

Thanks, @robertbennett1998 great work for this on PR #150