Move SSH signing function to library
Related issue: Automated/web commits (merge or web IDE commits... (gitlab#19185 - closed)
This MR:
- Moves SSH to a library
- Creates SigningKey interface
- GPG and SSH keys are implementing this interface
It's a preparational work for: gitlab!124218 (comment 1440760387)
It should also help with: #5335 (comment 1438711673)
Edited by Igor Drozdov