**Description**

Enabled list of cors headers origin allowed

**Use case / motivation**

I'm currently developping Django application working with apache airflow for some external work through api. From Django, user run dag and a js request wait for dag end. By this way, I enabled cors headers in airflow.cfg with correct url. But now, I've  environment (dev & prod). It could be useful to be able to set more than one url in airflow.cfg cors header origin allowed

Thank's in advance :) 

airflow/www/extensions/init_views.py
"""Initializes connection form"""
    lazy_add_provider_discovered_options_to_connection_form()
def init_error_handlers(app: Flask):
    """Add custom errors handlers"""
    from airflow.www import views
    app.register_error_handler(500, views.show_traceback)
    app.register_error_handler(404, views.not_found)
def set_cors_headers_on_response(response):
    """Add response headers"""
    allow_headers = conf.get('api', 'access_control_allow_headers')
    allow_methods = conf.get('api', 'access_control_allow_methods')
    allow_origin = conf.get('api', 'access_control_allow_origin')
    if allow_headers is not None:
        response.headers['Access-Control-Allow-Headers'] = allow_headers
    if allow_methods is not None:
        response.headers['Access-Control-Allow-Methods'] = allow_methods
    if allow_origin is not None:
        response.headers['Access-Control-Allow-Origin'] = allow_origin
    return response
def init_api_connexion(app: Flask) -> None: