ls: glob support for non-UTF-8 missing

[jtracey]

None of the available major globbing libraries, which we need for specifying ignore patterns, support anything other than &str.
There are three relevant issues I found, the resolution of any one of which would likely be sufficient for us:

• glob("*") does not support matching non-utf8 filenames rust-lang/glob#23
• glob() should take a Path not str rust-lang/glob#78,
• globset: allow building globs from OS strings BurntSushi/ripgrep#1250

[Arcterus]

I had a PR up for that in glob, but apparently a coworker broke it by force-pushing lol. I have no idea how much the code changed since then, but someone might be able to resurrect it (the PR is broken, but the commits are still there if you check the force-push message).