feat(croc): adds extension for sending and reciving files using croc

[FredrikMWold]

Adds a new croc extension for Vicinae that enables secure file transfer through simple send and receive commands.

What’s Included

• Send pick files/folders and get a transfer code to share with the receiver
• Receive enter a transfer code to download files, with an accept/reject prompt

Notes

• Requires croc to be installed on the host system