Add MatchOperator "Or", "And" and "Average" for patterns (#755)

* wip

* ...

* .

* ...

* ...

* path

* url

* b

* t

* client

* .

* RequestMessageMethodMatcherTests

* .

* h

* .

* fix tests

* .

src/WireMock.Net/Matchers/IObjectMatcher.cs

@@ -1,4 +1,4 @@
-namespace WireMock.Matchers
+namespace WireMock.Matchers
 {
     /// <summary>
     /// IObjectMatcher
@@ -10,6 +10,6 @@
         /// </summary>
         /// <param name="input">The input.</param>
         /// <returns>A value between 0.0 - 1.0 of the similarity.</returns>
-        double IsMatch(object input);
+        double IsMatch(object? input);
     }
 }