sftp-server: Add nanoseconds support

[David Newall]

On 3/9/21 11:26 pm, Opty wrote:
> please, consider adding nanoseconds support to sftp-server.

I'm not sure what time you want returned with nanosecond-resolution, 
but, perhaps you mean the creation or last modification time of remote 
files and directories.  I don't know what resolution SFTP provides but 
it can't be greater than the underlying filesystem.  Most of them have 
second-resolution.

I don't think openssh's sftp server can have a different resolution 
without breaking compatibility with every sftp client.