Add AFC (Apple File Conduit) KIO worker

It uses libimobiledevice to provide file system access to iOS devices.

Overview page afc:/

A folder

Inaccessible/untrusted device found when on afc:/

What works:

• Listing plugged in iOS devices
• Internal state also tracks adding/removal, also refreshing afc:/ overview reloads device list as there appears to be no signal for "device is now trusted"
• Listing directories, file birthtime/mtime, size
• Opening files (both small ones and large ones where it does multiple reads), even seamlessly through kiofuse
• Creating, editing files, copying onto and off the device
• Creating folders
• Renaming files
• Moving files
• Deleting files and folders (folders also recursively)
• file system free space (shows free space available to the user and might differ from what the device shows in Settings)

What wasn't tested:

• Seeking
• Setting mtime (our call after put works so I assume setModifiedTime also works)
• Truncating

It allows accessing app shared files via "Houearrest API" through a magic "Apps" folder. This is somewhat flaky especially on newer iOS but has become a lot better after I upgraded to neon 22.04.

@dfaure @meven @fvogt @sitter @ngraham