add support for env -S = env --split-string, to parse multiple arguments

actual

```
> shebangCommand('#!/usr/bin/env -S node -v');
'-S'
```

expected

```
> shebangCommand('#!/usr/bin/env -S node -v');
['node', '-v']
```

man env

```
-S, --split-string=S
process and split S into separate arguments; used to pass multiple arguments on shebang lines
```

currently, these shebang parsers fail

- https://www.npmjs.com/package/shebang-command
- https://www.npmjs.com/package/shebang
- https://www.npmjs.com/package/shebang-file

related issues

- https://github.com/pnpm/pnpm/issues/5575
- https://github.com/pnpm/cmd-shim/pull/42

quickfix

```js
function parseShebang(fileText) {
// based on https://github.com/pnpm/cmd-shim
// see also https://github.com/npm/cmd-shim
// examples:
// "#!/bin/sh" -> ["/bin/sh", ""]
// "#! /usr/bin/bash a b c" -> ["/usr/bin/bash", " a b c"]
// "#! /usr/bin/env -S bash a b c" -> ["bash", " a b c"]
// "#! /usr/bin/env -Sbash a b c" -> ["bash", " a b c"]
const shebangExpr = /^#!\s*(?:\/usr\/bin\/env\s+(?:-S)?)?\s*(\S+)(.*)$/;
let firstLineEnd = fileText.indexOf('\n');
if (firstLineEnd == -1) firstLineEnd = fileText.length;
const firstLine = fileText.slice(0, firstLineEnd).trimRight();
const shebang = firstLine.match(shebangExpr);
if (!shebang) return null;
const [_, arg0, args] = shebang;
return [arg0, args];
}
```

Start at the shebangCommand entry point used in the examples and inspect the package's existing parser tests. Cover /usr/bin/env -S forms so the command and multiple arguments match the expected ['node', '-v'] result, then run the test suite.

Written by the indexing model from the issue text.