Implement IApplicationFunctions & IQueryService commands (#823)

* Implement IApplicationFunctions & IQueryService commands

- Fix some nits in `IApplicationFunctions`
- Implement `QueryApplicationPlayStatistics` and `QueryApplicationPlayStatisticsByUid` checked by RE.
- Implement `QueryApplicationPlayStatisticsForSystem` and `QueryApplicationPlayStatisticsByUserAccountIdForSystem` checked by RE.
- Implement `QueryPlayStatisticsManager` to get/set played games statistics. We currently don't store any statistics because it's handled by qlaunch (or maybe am service?) on Switch.
We can add support later if games use returned statistics for something.

* Fix reviews

Ryujinx.HLE/HOS/Services/Sdb/Pdm/ResultCode.cs

@@ -0,0 +1,13 @@
+namespace Ryujinx.HLE.HOS.Services.Sdb.Pdm
+{
+    enum ResultCode
+    {
+        ModuleId       = 178,
+        ErrorCodeShift = 9,
+
+        Success = 0,
+
+        UserNotFound       = (101 << ErrorCodeShift) | ModuleId,
+        ServiceUnavailable = (150 << ErrorCodeShift) | ModuleId
+    }
+}