Of note: The rpm/yum thing seems to be coupled, so I put it into one
function that tries the yum helper and uses the rpm path otherwise.
Zypper is already its own thing, so this should only be used for yum
and probably dnf (does that still have the helper?)
Zypper can be dropped, as that already used a separate function in the file.
Apk can just be inlined - it's literally one line for installed and another for all packages.
This might be a bit over the top, but getting the information that a default priority threshold is used without knowing what that value is or how to find out might not be so useful after all. Thus, change the completion to include this information dynamically.
The dpkg-reconfigure command is used on Debian and Ubuntu based systems to reconfigure packages.
According to the relevant manpage's the commited completion file should be complete.
