Make the language server binary executable after download

[424ever]

Resolves #19
Draft because I'm unsure this repo is the correct place to fix the issue. Maybe it should be zed::download_file's job to carry over file permissions when extracting a zip file.

Note that zed::make_file_executable is a noop on non-unix platforms, so it shouldn't be an issue to call it here.

[424ever]

If this goes through, it might also be a good idea to update the following condition

if fs::metadata(path).map_or(false, |stat| stat.is_file()) {
    return Ok(path.clone());
}

to check for execute permissions, so that the lsp is downloaded again with the correct permissions, something like this:

if fs::metadata(path).map_or(false, |stat| {
    stat.is_file()
        && #[cfg(unix)]
        {
            const USER_HAS_EXEC_ACCESS: u32 = 0o100;
            (stat.permissions().mode() & USER_HAS_EXEC_ACCESS) != 0
        }
}) {
    return Ok(path.clone());
}

But note that this currently doesn't work because attributes on expressions are experimental: rust-lang/rust#15701.

[maxdeviant]

If this goes through, it might also be a good idea to update the following condition

if fs::metadata(path).map_or(false, |stat| stat.is_file()) {
    return Ok(path.clone());
}

to check for execute permissions, so that the lsp is downloaded again with the correct permissions, something like this:

if fs::metadata(path).map_or(false, |stat| {
    stat.is_file()
        && #[cfg(unix)]
        {
            const USER_HAS_EXEC_ACCESS: u32 = 0o100;
            (stat.permissions().mode() & USER_HAS_EXEC_ACCESS) != 0
        }
}) {
    return Ok(path.clone());
}

But note that this currently doesn't work because attributes on expressions are experimental: rust-lang/rust#15701.

It's moot either way, as we can't use platform cfg!s since this executes in Wasm instead of on the host platform.

[maxdeviant]

Thank you!