updater-ng: update to version 70.0.0

Added

• Change log that leaves minimal trace of changes updater performed stored in system.
• Support for FilesSignature field in packages. On mismatch it trigger reinstall.
• Support for files-sha256sum in packages as hash index

Fixed

• Subprocess call is now terminated way earlier thanks to SIGCHLD signal handling. This improves update time for any scripts spawning "daemon" processes that do not correctly redirect or close standard outputs.
• Reinstall of packages if some fields were formated differently in index than in package (updater no longer detects change by simple string comparison)

Changed

• Internal implementation of base64 replaced with base64c library.
• Utility opkg-create template and input format

Removed

• --state-log argument
• --task-log argument