account: Implement IManagerForApplication calls and IAsyncContext (#1466)

* account: Implement IManagerForApplication calls and IAsyncContext

This implement:
- IManagerForApplication::EnsureIdTokenCacheAsync (accordingly to RE) but the Async task is stubbed.
- IAsyncContext interface (accordingly to RE).
- IManagerForApplication::LoadIdTokenCache (checked with RE, and stubbed).

I've tried some games but now they needs some `sfdnsres` calls, some other boots and crashes with other issues.
Maybe we should disable the connection somewhere to lets the game think we are offline. I have done many attempts, without success, but since the code is here now, it's better than nothing.

(I've cleaned up `using` of IGeneralService too)

Closes #629 and closes #630

* change AccountId

* Fix gdkchan's comments

* use CompletedTask

Ryujinx.HLE/HOS/Services/Account/Acc/IAccountServiceForApplication.cs

@@ -160,7 +160,7 @@ namespace Ryujinx.HLE.HOS.Services.Account.Acc
         {
             if (_applicationLaunchProperty != null)
             {
-                return ResultCode.ApplicationLaunchPropertyAlreadyInit;
+                return ResultCode.Unknown41;
             }
 
             // The u64 argument seems to be unused by account.
@@ -282,7 +282,7 @@ namespace Ryujinx.HLE.HOS.Services.Account.Acc
             /*
             if (_applicationLaunchProperty != null)
             {
-                return ResultCode.ApplicationLaunchPropertyAlreadyInit;
+                return ResultCode.Unknown41;
             }
             */