Describe the bug

Previous to 0.101.0, the default behaviour for converting $env.PATH to a string before calling an external command was to not only handle the PATH/Path case issue, but also to expand individual paths using path expand. E.g:

$env.ENV_CONVERSIONS = {
    "PATH": {
        from_string: { |s| $s | split row (char esep) | path expand --no-symlink }
        to_string: { |v| $v | path expand --no-symlink | str join (char esep) }
    }
}

After 0.101.0, the case-sensitivity issue is handled internally, but $env.ENV_CONVERSIONS is now empty by default, so no path expansion is performed.

How to reproduce

1. Add a path to $env.PATH that requires expansion, for instance: $env.PATH = ($env.PATH | prepend [ "~/.cargo/bin" ]).
2. Run a program that needs to exec a command found in the above path (in my case, I was running trunk which was trying to run cargo metadata)
3. Observe the failure, as the executed program will have a $PATH variable containing the unexpanded ~/.cargo/bin path instead of the fully resolved one.

Expected behavior

I expected the default behaviour in 0.101.0 to match that of 0.100.0 and prior.

Configuration