yb-support-tool doesn't honour sendsafely dropzone properly

[jasonriddell]

yb-support-tool doesn't properly honour the sendsafely dropzone, meaning uploads don't get registered with the correct ticket in sendsafely and aren't linked to it.

http://support.sendsafely.com/hc/requests/234331

[jasonriddell]

The change was adding the keycode upload step, which the main branch was completely missing.

When a SendSafely Dropzone package is created, the server assigns recipients (e.g., the Zendesk integration). Each recipient has a PGP public key. Before finalizing the package, the client is supposed to:

• Fetch the recipients' public keys from the server
• Encrypt the client secret (the "keycode" that unlocks the package) using each recipient's PGP public key
• Upload each encrypted keycode back to the server, associated with the corresponding recipient

The previous code skips this entire step; it went straight from uploading file parts to finalizing the package. Without the encrypted keycodes, recipients had no way to decrypt the package, which is why the Zendesk integration never saw the uploads in the right sidebar.

I used the demo code from here: https://github.com/SendSafely/Code-Examples/blob/master/Dropzone%20Upload%20CLI/dropzoneUpload.js and used Cursor to identify key differences in the flow. It wasn't completely straightforward. SendSafely has a library for Node, which abstracts most of the work, though this was the difference that made the difference.