fix(opts command) run server on windows 10, cmd "opts utf8 on" doesn…

[wqliceman]

…'t work

When run on windows10, cmd " opts utf8 on" "site help" parse error. because in extension cmd is "UTF8" is UPPER.

[15:39:15 DBG] USER tester [15:39:15 DBG] 331 User tester logged in, needs password [15:39:15 INF] Connection closed [15:39:15 DBG] PASS **** (password omitted) [15:39:15 DBG] The root directory for tester is /root\tester [15:39:15 DBG] 230 Password ok, FTP server ready [15:39:15 DBG] opts utf8 on [15:39:51 DBG] 500 Syntax error, command unrecognized.

OptsCommandHandler.Process public override async Task<IFtpResponse?> Process(FtpCommand command, CancellationToken cancellationToken) { var argument = FtpCommand.Parse(command.Argument); if (!Extensions.TryGetValue(argument.Name, out var extension)) <======= need to UPPER { return new FtpResponse(500, T("Syntax error, command unrecognized.")); }

        return await extension.Process(argument, cancellationToken).ConfigureAwait(false);
    }

[fubar-coder]

I believe that Extensions should use OrdinalIgnoreCase instead, but I'll look into it.