Fix new Delete with body missing from IWireMockAdminApi interface (#413)

* Fix new Delete with body missing from IWireMockAdminApi interface

* Admin Delete with mappings in body (#409)

* Add unit test for delete with body

* change order of checks for readability. looks nicer.

* Allow body in DELETE requests

* Fix unit tests according to DELETE supporting body

* Re-run CI

* Fix DELETE with body unit test

* Fix ElementAt index in mappings list

* Fix DELETE with body unit test

* Fix theory tag must be accompanied by some InlineData or Member

* Fix didn't use correct checking syntax

* Fix wrap entire unit test in if region

src/WireMock.Net.RestClient/IWireMockAdminApi.cs

@@ -74,6 +74,14 @@ namespace WireMock.Client
         [Delete("mappings")]
         Task<StatusModel> DeleteMappingsAsync();
 
+        /// <summary>
+        /// Delete mappings according to GUIDs
+        /// </summary>
+        /// <param name="mappings">MappingModels</param>
+        [Delete("mappings")]
+        [Header("Content-Type", "application/json")]
+        Task<StatusModel> DeleteMappingsAsync([Body] IList<MappingModel> mappings);
+
         /// <summary>
         /// Delete (reset) all mappings.
         /// </summary>