Generate valid C# when an external module has an unsupported operator

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/Generator/Passes/MoveFunctionToClassPass.cs

@@ -24,8 +24,7 @@ namespace CppSharp.Passes
 
             Class @class = FindClassToMoveFunctionTo(function);
 
-            if (@class == null ||
-                @class.TranslationUnit.Module != function.TranslationUnit.Module)
+            if (@class == null)
                 return false;
 
             // Create a new fake method so it acts as a static method.

tests/NamespacesDerived/NamespacesDerived.cpp

@@ -92,3 +92,8 @@ DerivedFromSecondaryBaseInDependency::DerivedFromSecondaryBaseInDependency()
 DerivedFromSecondaryBaseInDependency::~DerivedFromSecondaryBaseInDependency()
 {
 }
+
+bool operator<<(const Base& b, const char* str)
+{
+    return false;
+}

tests/NamespacesDerived/NamespacesDerived.h

@@ -87,6 +87,8 @@ public:
     ~DerivedFromSecondaryBaseInDependency();
 };
 
+DLL_API bool operator<<(const Base& b, const char* str);
+
 namespace NamespacesBase
 {
     class DLL_API ClassInNamespaceNamedAfterDependency