loadFromFile static method
Loads and parses a .gitignore file at path.
Returns an empty parser if the file does not exist.
Implementation
static Future<GitignoreParser> loadFromFile(String path) async {
final file = File(path);
if (!await file.exists()) return GitignoreParser._([]);
final content = await file.readAsString();
return GitignoreParser.parse(content);
}