Rollup merge of #82121 - lopopolo:pathbuf-osstring-extend, r=joshtriplett
Rollup merge of #82121 - lopopolo:pathbuf-osstring-extend, r=joshtriplett

Implement Extend and FromIterator for OsString

Add the following trait impls:

- `impl Extend<OsString> for OsString`
- `impl<'a> Extend<&'a OsStr> for OsString`
- `impl FromIterator<OsString> for OsString`
- `impl<'a> FromIterator<&'a OsStr> for OsString`

Because `OsString` is a platform string with no particular semantics, concatenating them together seems acceptable.

I came across a use case for these trait impls in https://github.com/artichoke/artichoke/pull/1089:

Artichoke is a Ruby interpreter. Its CLI accepts multiple `-e` switches for executing inline Ruby code, like:

```console
$ cargo -q run --bin artichoke -- -e '2.times {' -e 'puts "foo: #{__LINE__}"' -e '}'
foo: 2
foo: 2
```

I use `clap` for command line argument parsing, which collects these `-e` commands into a `Vec<OsString>`. To pass these commands to the interpreter for `Eval`, I need to join them together. Combining these impls with `Iterator::intersperse` https://github.com/rust-lang/rust/issues/79524 would enable me to build a single bit of Ruby code.

Currently, I'm doing something like:

```rust
let mut commands = commands.into_iter();
let mut buf = if let Some(command) = commands.next() {
    command
} else {
    return Ok(Ok(()));
};
for command in commands {
    buf.push("\n");
    buf.push(command);
}
```

If there's interest, I'd also like to add impls for `Cow<'a, OsStr>`, which would avoid allocating the `"\n"` `OsString` in the concatenate + intersperse use case.

aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust