aoc/am: Cleanup aoc service and stub am calls (#2414)

* aoc/am: Cleanup aoc service and stub am calls

This PR implement aoc call `GetAddOnContentListChangedEventWithProcessId` (Closes #2408) and `CreateContentsServiceManager`. Additionnally, a big cleanup (checked by RE on latest firmware) is made on the whole service. I've added `CountAddOnContent`, `ListAddOnContent` and `GetAddonContentBaseId` for games which require version `1.0.0-6.2.0` too.

Am service call `ReportUserIsActive` is stubbed (checked by RE, closes #2413).

Since some logic in the service (aoc) which handle the DLCs has been changed, it could be nice to have some testing to be sure there is no regression.

* Remove wrong check

* Addresses gdkchan feedback

* Fix GetAddOnContentLostErrorCode

* fix null pid in services

* Add missing comment

* remove leftover comment

Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/SystemAppletProxy/ISelfController.cs

@@ -285,6 +285,17 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Sys
             return ResultCode.Success;
         }
 
+        [CommandHipc(65)]
+        // ReportUserIsActive()
+        public ResultCode ReportUserIsActive(ServiceCtx context)
+        {
+            // TODO: Call idle:sys ReportUserIsActive when implemented.
+
+            Logger.Stub?.PrintStub(LogClass.ServiceAm);
+
+            return ResultCode.Success;
+        }
+
         [CommandHipc(68)]
         // SetAutoSleepDisabled(u8)
         public ResultCode SetAutoSleepDisabled(ServiceCtx context)