settings: implement KeyValueStore (#1659)

* settings: implement KeyValueStore and dependencies

* settings: update KeyValueStore for recent refactoring

* settings: address feedback

libraries/libstratosphere/include/stratosphere/spl/spl_api.hpp

@@ -60,6 +60,12 @@ namespace ams::spl {
         return static_cast<HardwareState>(v);
     }
 
+    inline RetailInteractiveDisplayState GetRetailInteractiveDisplayState() {
+        u64 v;
+        R_ABORT_UNLESS(::ams::spl::GetConfig(std::addressof(v), ::ams::spl::ConfigItem::RetailInteractiveDisplayState));
+        return static_cast<RetailInteractiveDisplayState>(v);
+    }
+
     inline u64 GetDeviceIdLow() {
         u64 v;
         R_ABORT_UNLESS(::ams::spl::GetConfig(std::addressof(v), ::ams::spl::ConfigItem::DeviceId));

libraries/libstratosphere/include/stratosphere/spl/spl_types.hpp

@@ -138,6 +138,11 @@ namespace ams::spl {
         MemoryArrangement_Count,
     };
 
+    enum RetailInteractiveDisplayState {
+        RetailInteractiveDisplayState_Disabled = 0,
+        RetailInteractiveDisplayState_Enabled  = 1,
+    };
+
     struct BootReasonValue {
         union {
             struct {
@@ -217,7 +222,7 @@ namespace ams::spl {
         IsDevelopmentFunctionEnabled  = 11,
         KernelConfiguration           = 12,
         IsChargerHiZModeEnabled       = 13,
-        QuestState                    = 14,
+        RetailInteractiveDisplayState = 14,
         RegulatorType                 = 15,
         DeviceUniqueKeyGeneration     = 16,
         Package2Hash                  = 17,