Clipboard action now sets an expiration timer

WIP Max History count (back-end done, front-end todo)

ModernKeePass.Application/Common/Interfaces/IDatabaseProxy.cs

@@ -22,6 +22,7 @@ namespace ModernKeePass.Application.Common.Interfaces
         string FileAccessToken { get; set; }
         int Size { get; set; }
         bool IsDirty { get; set; }
+        int MaxHistoryCount { get; set; }
 
         Task Open(byte[] file, Credentials credentials);
         Task ReOpen(byte[] file);