Fix check for installed packages and removed package

Updater preserves removed packages in index if they at time of removal had some modified configuration files. Such packages are removed and should be reported as such. There is also no control file on filesystem.

This fixes missing control file error by just not reading control file if it is not present. This has no impact as info is not available about that package and should not be required anyway.

This also fixes installed method by properly checking status fields.

Reference for opkg status: https://gitlab.nic.cz/turris/updater/updater/-/blob/master/docs/opkg.adoc