docs: Remove "src" from directories doxygen should check for documentation

The documentation should be moved to the headers and generated from there.
afc: Unify argument names for some functions to match overall API
afc: Cleanup and reformat documentation comments
afc: Add documentation for afc_dictionary_free()
afc: Implement afc_remove_path_and_contents() for recursive deletion

Only available on iOS 6 and later.
lockdown: Added lockdownd_start_service_with_escrow_bag

Signed-off-by: Martin Szulecki <m.szulecki@libimobiledevice.org>
idevicebackup2: Use correct label for lockdown requests
idevicebackup2: Use macro instead of plain AFC service name
idevicebackup2: Fix backup failure for passcode devices entering lock screen

A device would report "ErrorCode 1: Error copying keychain data
(MBErrorDomain/1)" if a device entered lock state and had a passcode enabled
during the backup or restore process. To prevent this, an escrow bag must be
sent when starting the service to keep the operation "alive".