Convert FirmwareOption to a readonly struct

src/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs

@@ -37,13 +37,7 @@ namespace BizHawk.Emulation.Common
 						isBad: isBad);
 
 			void Option(string systemId, string id, in FirmwareFile ff, FirmwareOptionStatus status = FirmwareOptionStatus.Acceptable)
-				=> options.Add(new FirmwareOption
-				{
-					ID = new(systemId, id),
-					Hash = ff.Hash,
-					Status = ff.IsBad ? FirmwareOptionStatus.Bad : status,
-					Size = ff.Size
-				});
+				=> options.Add(new(new(systemId, id), ff.Hash, ff.Size, ff.IsBad ? FirmwareOptionStatus.Bad : status));
 
 			void Firmware(string systemId, string id, string desc)
 				=> records.Add(new FirmwareRecord

src/BizHawk.Emulation.Common/Database/FirmwareOption.cs

@@ -1,15 +1,25 @@
+#nullable enable
+
 namespace BizHawk.Emulation.Common
 {
-	public sealed class FirmwareOption
+	public readonly struct FirmwareOption
 	{
-		public string Hash { get; set; }
+		public readonly string Hash;
 
-		public FirmwareID ID { get; set; }
+		public readonly FirmwareID ID;
 
 		public bool IsAcceptableOrIdeal => Status == FirmwareOptionStatus.Ideal || Status == FirmwareOptionStatus.Acceptable;
 
-		public long Size { get; set; }
+		public readonly long Size;
 
-		public FirmwareOptionStatus Status { get; set; }
+		public readonly FirmwareOptionStatus Status;
+
+		public FirmwareOption(FirmwareID id, string hash, long size, FirmwareOptionStatus status)
+		{
+			Hash = hash;
+			ID = id;
+			Size = size;
+			Status = status;
+		}
 	}
 }