Change the naming scheme for class field members

I'm not a fan of Hungarian notation, but C++ kind of needs it with its
implicit `this`. And of all the common options for this, I find
suffixing members with an underscore the least offensive one.

src/common/serialization/vst3/host-context-proxy.h

@@ -98,11 +98,11 @@ class Vst3HostContextProxy : public YaHostApplication,
      * global host context passed to the module's plugin factory.
      */
     inline std::optional<size_t> owner_instance_id() const noexcept {
-        return arguments.owner_instance_id;
+        return arguments_.owner_instance_id;
     }
 
    private:
-    ConstructArgs arguments;
+    ConstructArgs arguments_;
 };
 
 #pragma GCC diagnostic pop