The upstream open crate keeps making stuff async/blocking/not-working on
windows, so this is a step towards removing this dependency.
refs: https://github.com/wez/wezterm/issues/3288
- Removes closures and function calls for types that implement default:
```rust
// Change
let _my_str = get_str().unwrap_or(String::new);
// To
let _my_str = get_str().unwrap_or_default();
```
- Uses the `.cloned()/.copied()` methods where possible
- Use function pointer instead of simple closure
May improve performace, as closures generate more code, and this might
unlock some inlining opportunities.
Otherwise we can block the gui waiting for eg: a freshly opened firefox to
terminate.
See also comment worrying about this in
75066cb522.
That fear was realized but now resolved!
refs: https://github.com/wez/wezterm/issues/2245
Main thing to note here is that the open crate has deprecated
open::that_in_background, but made open::that non-blocking.
I think this is OK, but I'm a little cagey about what will
happen with this on Windows. We may need to spawn our own
thread for this if things go awry.
