Create WireMock.Net.MimePart project (#1300)

* Create WireMock.Net.MimePart project

* .

* REFACTOR

* ILRepack

* --

* ...

* x

* x

* .

* fix

* public class MimePartMatcher

* shared

* min

* .

* <!--<DelaySign>true</DelaySign>-->

* Update README.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/WireMock.Net.Minimal/MappingRegistrationCallback.cs

@@ -0,0 +1,11 @@
+// Copyright © WireMock.Net
+
+namespace WireMock
+{
+    /// <summary>
+    /// The registration callback.
+    /// </summary>
+    /// <param name="mapping">The mapping.</param>
+    /// <param name="saveToFile">Optional boolean to indicate if this mapping should be saved as static mapping file.</param>
+    public delegate void RegistrationCallback(IMapping mapping, bool saveToFile = false);
+}