Suggestion: Import and export ("backup") a list of currently installed packages #121
Description
Storeman has gained the feature to import and export ("backup") of the list of currently installed packages a few years ago. It was very well received, because that allows for easy migration of the installed packages (list) between devices and when flashing the same device anew.
The export simply creates a list of the currently installed packages from the SailfishOS:Chum repository (¿or all repositories?). I think that a simple, human readable format (with one package per line) is preferable, because it is at most a few hundred packages (= lines) long. One might consider to store the whole %{name}-%{version}-%{release} tuple, because unneeded information can still be discarded on import. I also suggest to consider a simple (but also human readable) header denoting the software and its version, which created the file. And the file needs a "sounding" (i.e., easily recognisable and self-explanatory) name, e.g., sailfishos-chum_packages-backup.txt.
It also makes sense to look (and maybe steal and adapt) Storeman's code and to consider to conform to the file format Storeman is using for this (if it is fulfilling the aforementioned requirements).
The import allows for selecting a backup file, parses it and installs the packages listed, which are still available. I actually never used Storeman's import function, so I cannot tell what Storeman does in detail.