**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/configuration.py
path = _default_config_file_path('default_airflow.cfg')
    with open(path) as fh:
        return fh.read()
@functools.lru_cache(maxsize=None)
def _TEST_CONFIG():
    path = _default_config_file_path('default_test.cfg')
    with open(path) as fh:
        return fh.read()
_deprecated = {
    'DEFAULT_CONFIG': _DEFAULT_CONFIG,
    'TEST_CONFIG': _TEST_CONFIG,
    'TEST_CONFIG_FILE_PATH': functools.partial(_default_config_file_path, ('default_test.cfg')),
    'DEFAULT_CONFIG_FILE_PATH': functools.partial(_default_config_file_path, ('default_airflow.cfg')),
}
def __getattr__(name):
    if name in _deprecated:
        warnings.warn(
            f"{__name__}.{name} is deprecated and will be removed in future",
            DeprecationWarning,
            stacklevel=2,
        )