curlsftpsink: Add support for sha256 fingerprint
Copied from https://gitlab.freedesktop.org//gstreamer/gst-plugins-bad/-/merge_requests/2515
Added property for sha256 fingerprint.
Copied from https://gitlab.freedesktop.org//gstreamer/gst-plugins-bad/-/merge_requests/2515
Added property for sha256 fingerprint.