Support user-level file system mounting

[chipsenkbeil]

This would be a neat long-term feature to support a user-level file system similar to SSHFS.

• Windows has a Cloud files api for Windows 10 and later that seems like a reasonable path forward. Stack overflow has a good topic on this.
• MacOS has a [FileProvider API]*https://developer.apple.com/documentation/fileprovider) for remote file synchronization, maybe using icrate or some other binding. iTerm2 example in Swift and associated info.plist.
• Filesystem in Userspace is supported on pretty much everything, but the support and requirements vary to set it up. SSHFS does this. See fuser crate for modern Rust libary.