general: Make most settings a BasicSetting

Creates a new BasicSettings class in common/settings, and forces setting
a default and label for each setting that uses it in common/settings.
Moves defaults and labels from both frontends into common settings.
Creates a helper function in each frontend to facillitate reading the
settings now with the new default and label properties.

Settings::Setting is also now a subclass of Settings::BasicSetting. Also
adds documentation for both Setting and BasicSetting.

src/core/hle/service/acc/profile_manager.cpp

@@ -48,7 +48,8 @@ ProfileManager::ProfileManager() {
         CreateNewUser(UUID::Generate(), "yuzu");
     }
 
-    auto current = std::clamp<int>(Settings::values.current_user, 0, MAX_USERS - 1);
+    auto current =
+        std::clamp<int>(static_cast<s32>(Settings::values.current_user), 0, MAX_USERS - 1);
 
     // If user index don't exist. Load the first user and change the active user
     if (!UserExistsIndex(current)) {