Add WithBody with IDictionary (form-urlencoded values) (#903)

* .

* x

* fx

* fix

* f

* tests

* fix tests

* add tst

src/WireMock.Net.Abstractions/Models/IBodyData.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Text;
 using WireMock.Types;
 
@@ -38,6 +39,11 @@ public interface IBodyData
     /// </summary>
     string? BodyAsString { get; set; }
 
+    /// <summary>
+    /// The body as Form UrlEncoded dictionary.
+    /// </summary>
+    IDictionary<string, string>? BodyAsFormUrlEncoded { get; set; }
+
     /// <summary>
     /// The detected body type (detection based on body content).
     /// </summary>