feature: allow transfering modification and access time in source mode

[bramvdbogaerde]

Currently we can only set permissions on the remote when copying files to the remote. However, the SCP protocol also allows sending T messages that contain modification and access time for the files being transferred.

Thus the goal of this issue is to implement functionality such that access and modification time can also be transferred from the client to the remote server. A similar issue (#63) was created and in response PR #81 was submitted and merged to provide this functionality for copying files from the remote to the client.

This issue aims to track progress of this feature for transfers from the client to the remote (source mode).