account: Adds AccountManager (#2184)

* account: Adds Account Manager

In a way to have Custom User Profiles merged in master faster, this PR adds a `AccountManager` class (based on `AccountUtils` class) and the following changes have been made:
- Adds a "default profile values" which were the old hardcoded ones.
- The image profile is moved to the Account service folder.
- The hardcoded UserId for the savedata is now using the `AccountManager` last opened one.
- The DeviceId in Mii service is changed to the right value (checked by REd sys:set call).

* Fix csproj

* Addresses gdkchan's comments

* Fix UserProfile fields

* Fix mii GetDeviceId()

* Update Ryujinx.HLE.csproj

Ryujinx.HLE/HOS/Services/Mii/Helper.cs

@@ -1,5 +1,4 @@
-using Ryujinx.HLE.HOS.SystemState;
-using Ryujinx.HLE.Utilities;
+using Ryujinx.HLE.Utilities;
 using System;
 using System.Buffers.Binary;
 
@@ -32,7 +31,7 @@ namespace Ryujinx.HLE.HOS.Services.Mii
         public static UInt128 GetDeviceId()
         {
             // FIXME: call set:sys GetMiiAuthorId
-            return SystemStateMgr.DefaultUserId.ToUInt128();
+            return new UInt128(0, 1);
         }
 
         public static ReadOnlySpan<byte> Ver3FacelineColorTable => new byte[] { 0, 1, 2, 3, 4, 5 };