This modifies the strv in-place, replacing strings with their escaped
version. It's mostly just a convenience function for when you need to
join a strv together because it's passed as a string to something, and
the separator needs escaping.
strv_split_extract is to strv_split_quotes as extract_first_word was to
unquote_first_word.
Now there's extract_first_word for extracting a single argument,
extract_many_words for extracting a bounded number of arguments,
and strv_split_extract for extracting an arbitrary number of arguments.
Richard Maw