Initial support for converting the mappings to a Pact(flow) json file (#748)

* WithDescription

* WithConsumer / WithProvider

* x

* .

* .

* .

* .

* fix

* pact

* nullable

* ficx

* .

* fix

src/WireMock.Net/Pact/Models/V2/ProviderState.cs

@@ -0,0 +1,11 @@
+using System.Collections.Generic;
+
+namespace WireMock.Pact.Models.V2
+{
+    public class ProviderState
+    {
+        public string Name { get; set; }
+
+        public IDictionary<string, string> Params { get; set; }
+    }
+}