修复 symbol obfuscation rule文件中存在不在混淆列表的程序集时，BuildRuleResultCaches抛出空引用异常的bug

com.code-philosophy.obfuz/Editor/ObfusPasses/SymbolObfus/Policies/ConfigurableRenamePolicy.cs

@@ -617,6 +617,10 @@ namespace Obfuz.ObfusPasses.SymbolObfus.Policies
             foreach (AssemblyRuleSpec assSpec in _assemblyRuleSpecs.Values.SelectMany(arr => arr))
             {
                 ModuleDef module = _assembliesToObfuscate.FirstOrDefault(m => m.Assembly.Name == assSpec.assemblyName);
+                if (module == null)
+                {
+                    continue;
+                }
                 List<TypeDef> types = module.GetTypes().ToList();
                 foreach (TypeRuleSpec typeSpec in assSpec.types)
                 {