fix: leading backslash on the controller path break the normalization function

[francescovallone]

What happened

When creating a controller with a leading slash the normalization function can't correctly normalize the routing path resulting in the impossiiblity to find the RouteSpec blocking the application.

Code

class AppController extends Controller {

  AppController({super.path = '/api/v1/periodic-table/'}){
    on(BenchRoute(path: '/element'), _handleElement);
    on(BenchRoute(path: '/shells'), _handleShells);
  }
  
  Future<Response> _handleElement(RequestContext context) async {
    if(!context.queryParameters.containsKey('symbol')){
      throw BadRequestException(message: 'Symbol is required');
    }
    final String symbol = context.queryParameters['symbol'];
    final Map<String, dynamic> element = await context.use<AppProvider>().getElement(symbol);

    return Response.json(element);
  }

  Future<Response> _handleShells(RequestContext context) async {
    if(!context.queryParameters.containsKey('symbol')){
      throw BadRequestException(message: 'Symbol is required');
    }
    final String symbol = context.queryParameters['symbol'];
    final Map<String, dynamic> shells = await context.use<AppProvider>().getShells(symbol);
    return Response.json(shells);
  }
}

What should have happened

The normalization function should take care of this edge-case making the router work with no errors.