So far I avoided adding license headers to meson files, but they are pretty
big and important and should carry license headers like everything else.
I added my own copyright, even though other people modified those files too.
But this is mostly symbolic, so I hope that's OK.
`systemctl default` uses job mode `isolate` (see `action_table`).
The job mode option is ignored.
Note that exiting the emergency shell service by using e.g.
`systemctl isolate multi-user` or `systemctl start multi-user.target`
already kills `emergency.service`. There's only a potential conflict
between your command and the command in systemd-sulogin-shell if you run
something like `systemctl start --no-block multi-user.target; exit`.
Which is nothing like what we told them to do :).
They require a writable /tmp dir (in the bash implementation).
Let's use echo, and not 'echo -e' since that doesn't seem to be completely
portable.
Fixes#6052.
The indentation for emacs'es meson-mode is added .dir-locals.
All files are reindented automatically, using the lasest meson-mode from git.
Indentation should now be fairly consistent.
The emergency.service and rescue.service units have become rather
convoluted. We spawn multiple shells and the help text spans multiple lines
which makes the units hard to read.
Move the logic into a single shell script and call that via ExecStart.
