PropertiesParser constructor

A parser for Java-style properties files.

Supports key=value pairs, comments (# and !), line continuations (), and nested properties using dot notation. Preserves special property values like #{} and @{} for later resolution.

Example usage:

void main() {
  final parser = PropertiesParser();

  final config = parser.parse('host=localhost\nport=8080');
  print(config['host']); // Output: localhost

  final config = parser.parseAsset(asset);
  print(config['host']); // Output: localhost

  final config = parser.parseFile('config.properties');
  print(config['host']); // Output: localhost
}