Implement mii:u and mii:e entirely (#955)

* Implement mii:u and mii:e entirely

Co-authored-by: AcK77 <Acoustik666@gmail.com>

This commit implement the mii service accurately.

This is based on Ac_k work but was polished and updated to 7.x.

Please note that the following calls are partially implemented:

- Convert: Used to convert from old console format (Wii/Wii U/3ds)
- Import and Export: this is shouldn't be accesible in production mode.

* Remove some debug leftovers

* Make it possible to load an arbitrary mii database from a Switch

* Address gdk's comments

* Reduce visibility of all the Mii code

* Address Ac_K's comments

* Remove the StructLayout of DatabaseSessionMetadata

* Add a missing line return in DatabaseSessionMetadata

* Misc fixes and style changes

* Fix some issues from last commit

* Fix database server metadata UpdateCounter in MarkDirty (Thanks Moose for the catch)

* MountCounter should only be incremented when no error is reported

* Fix FixDatabase

Co-authored-by: Alex Barney <thealexbarney@gmail.com>

Ryujinx.HLE/HOS/Services/Account/Acc/Types/UserId.cs

@@ -1,4 +1,5 @@
 using LibHac.Account;
+using Ryujinx.HLE.Utilities;
 using System;
 using System.IO;
 using System.Linq;
@@ -73,9 +74,14 @@ namespace Ryujinx.HLE.HOS.Services.Account.Acc
             return HashCode.Combine(Low, High);
         }
 
-        public Uid ToLibHacUid()
+        public readonly Uid ToLibHacUid()
         {
             return new Uid((ulong)High, (ulong)Low);
         }
+
+        public readonly UInt128 ToUInt128()
+        {
+            return new UInt128(Low, High);
+        }
     }
 }