**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
"""Get Path to airflow.cfg path"""
    if 'AIRFLOW_CONFIG' not in os.environ:
        return os.path.join(airflow_home, 'airflow.cfg')
    return expand_env_var(os.environ['AIRFLOW_CONFIG'])
def _parameterized_config_from_template(filename) -> str:
    TEMPLATE_START = '# ----------------------- TEMPLATE BEGINS HERE -----------------------\n'
    path = _default_config_file_path(filename)
    with open(path) as fh:
        for line in fh:
            if line != TEMPLATE_START:
                continue
            return parameterized_config(fh.read().strip())
    raise RuntimeError(f"Template marker not found in {path!r}")
def parameterized_config(template):
    """
    Generates a configuration from the provided template + variables defined in
    current scope
    :param template: a config content templated with {{variables}}
    """
    all_vars = {k: v for d in [globals(), locals()] for k, v in d.items()}
    return template.format(**all_vars)
def get_airflow_test_config(airflow_home):
    """Get path to unittests.cfg"""
    if 'AIRFLOW_TEST_CONFIG' not in os.environ:
        return os.path.join(airflow_home, 'unittests.cfg')
    return expand_env_var(os.environ['AIRFLOW_TEST_CONFIG'])
def _generate_fernet_key():
    from cryptography.fernet import Fernet
    return Fernet.generate_key().decode()
def initialize_config():