settings_common: Use a vector in category linkage

Improve storage requirements.

src/common/settings_common.h

@@ -66,7 +66,7 @@ class Linkage {
 public:
     explicit Linkage(u32 initial_count = 0);
     ~Linkage();
-    std::map<Category, std::forward_list<BasicSetting*>> by_category{};
+    std::map<Category, std::vector<BasicSetting*>> by_category{};
     std::vector<std::function<void()>> restore_functions{};
     u32 count;
 };