The `\0` being used to refer to the whole match is a GNU
extension. On other implementations of sed, this will simply
replace the each matched line with `	0;`, resulting in symbols
being missing in the NetworkManager executable, which breaks the
wifi plugin and others.

Use `&` instead, which behaves as expected in all implementations.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1562

See `man ovs-vswitchd.conf.db` for documentation of "other_config" keys.

https://bugzilla.redhat.com/show_bug.cgi?id=2151455

We get this wrong *very* often.

It just feels nicer to be explicit about the filenames and
not rely on a specific naming.

Also, in meson we can directly pass the target as argument, which
expands to the filename but also adds a dependency.

Found by lgtm.com.

We also need to build with python2. No f-strings.

Fixes: 8fc7b6df12ed ('tools: rework generating documentation from libnm meta data')

"nm-setting-ip-config.c" is a base class for IPv4 and IPv6 settings. So
far, any tags there were ignored, which was not obvious. It can be
useful to document common properties there. Well, maybe every property
better has a IPv4/IPv6 specific text, but that should not be a technical
limitation of the tool. So also honor the base file for "ipv4" and
"ipv6" settings.

When doing that, the settings are no longer processed in the order as
they are provided on the command line. Because, one file would be parsed
twice, it wouldn't make much sense. Instead, sort the my setting name.
The advantage is that the generated XML is independent from the order
that make/meson passes to the tool.

If the information is missing, the entire attribute should not be there.
Don't set it to the empty word.

Also, don't alias the "variable" attribute to the "name". It's not clear
what the "variable" fields is supposed to mean, but if it's not
explicitly set, don't make up the information. If a user of that
information cares, the can always fallback to the "name".