cores rework (#505)

This PR changes the core count to be defined in the device instead of
being a const value.
This is mostly a change for future features I want to implement and
should not impact any functionality.
The console will now log the range of cores requested from the
application, and for now, if the requested range is not 0 to 2 (the 3
cores used for application emulation), it will give an error message
which tells the user to contact me on discord. I'm doing this because
I'm interested in finding applications/games that don't use 3 cores and
the error will be removed in the future once I've gotten enough data.

src/Ryujinx.HLE/Switch.cs

@@ -32,6 +32,8 @@ namespace Ryujinx.HLE
         public TamperMachine TamperMachine { get; }
         public IHostUIHandler UIHandler { get; }
 
+        public int CpuCoresCount = 4; //Switch 1 has 4 cores
+
         public VSyncMode VSyncMode { get; set; } = VSyncMode.Switch;
         public bool CustomVSyncIntervalEnabled { get; set; } = false;
         public int CustomVSyncInterval { get; set; }