Horde: Reduce peak memory usage when building workspace snapshots. Was previously keeping references to Memory<byte> ranges within a much larger buffer, preventing them from being GC'd.

[CL 16867148 by Ben Marsh in ue5-main branch]

Engine/Source/Programs/Shared/EpicGames.Core/Utf8String.cs

@@ -86,6 +86,17 @@ namespace EpicGames.Core
 			this.Memory = new ReadOnlyMemory<byte>(Buffer, Offset, Length);
 		}
 
+		/// <summary>
+		/// Duplicate this string
+		/// </summary>
+		/// <returns></returns>
+		public Utf8String Clone()
+		{
+			byte[] NewBuffer = new byte[Memory.Length];
+			Memory.CopyTo(NewBuffer);
+			return new Utf8String(NewBuffer);
+		}
+
 		/// <summary>
 		/// Tests two strings for equality
 		/// </summary>