Update ftp links

[genomax]

@ewels Can ftp links be updated to http/https in sra-explorer? Since browsers no longer allow FTP by default it would be beneficial to get http links instead.

[ewels]

Sure, we can look into that at least as an option (assuming that there are predictable http URLs? Or that the APIs return them?)

But who is downloading big genomics datasets through the browser? Surely most transfers would be done on the command line or with dedicated file transfer tools, which should handle FTP?