Add unit test for generic class + change generated filename (#50)

tests/ProxyInterfaceSourceGeneratorTests/Source/Generic.cs

@@ -0,0 +1,10 @@
+namespace ProxyInterfaceSourceGeneratorTests.Source
+{
+    public class Generic<T>
+    {
+        public T Test(T value)
+        {
+            return value;
+        }
+    }
+}

tests/ProxyInterfaceSourceGeneratorTests/Source/IGeneric.cs

@@ -0,0 +1,6 @@
+namespace ProxyInterfaceSourceGeneratorTests.Source
+{
+    public partial interface IGeneric
+    {
+    }
+}