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.
New fish_indent does that too, so this will make any future reformatting
diffs smaller.
Done using either of:
perl -pi -e 'undef $/; s/\n*$/\n/' share/**.fish
kak -n -f '<a-/>\n*<ret>d' share/**.fish
