Support `--quoting-style` like `ls` (and quote filenames with spaces by default)

When a filename ends in a space, there is no indication. Compare this with GNU ls, which encloses filenames with spaces in quotes.

$ touch hello
$ ls
hello
$ exa
hello
$ touch 'hello '
$ ls
 hello	'hello '
$ exa
hello   hello

As an aside on the example above, GNU ls sorts 'hello ' after 'hello' while exa sorts them the other way round.