Embedded images replaced with cid linked resources. (#313)

* Added logic to replace embedded images with linked resources

* Added alt text for images and replaced NewtonSoft with Text.Json

* Fix draft mime preparation

* Fix crashes for signatures without images.

---------

Co-authored-by: Burak Kaan Köse <bkaankose@outlook.com>

Wino.Core.Domain/Models/Reader/ImageInfo.cs

@@ -0,0 +1,12 @@
+using System.Text.Json.Serialization;
+
+namespace Wino.Core.Domain.Models.Reader;
+
+public class ImageInfo
+{
+    [JsonPropertyName("data")]
+    public string Data { get; set; }
+
+    [JsonPropertyName("name")]
+    public string Name { get; set; }
+}

Wino.Core.Domain/Models/Reader/WebViewMessage.cs

@@ -1,4 +1,4 @@
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 
 namespace Wino.Core.Domain.Models.Reader
 {
@@ -7,10 +7,10 @@ namespace Wino.Core.Domain.Models.Reader
     /// </summary>
     public class WebViewMessage
     {
-        [JsonProperty("type")]
+        [JsonPropertyName("type")]
         public string Type { get; set; }
 
-        [JsonProperty("value")]
+        [JsonPropertyName("value")]
         public string Value { get; set; }
     }
 }