**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
"""Historical getsection"""
    warnings.warn(
        "Accessing configuration method 'getsection' directly from the configuration module is "
        "deprecated. Please access the configuration from the 'configuration.conf' object via "
        "'conf.getsection'",
        DeprecationWarning,
        stacklevel=2,
    )
    return conf.getsection(*args, **kwargs)
def has_option(*args, **kwargs):
    """Historical has_option"""
    warnings.warn(
        "Accessing configuration method 'has_option' directly from the configuration module is "
        "deprecated. Please access the configuration from the 'configuration.conf' object via "
        "'conf.has_option'",
        DeprecationWarning,
        stacklevel=2,
    )
    return conf.has_option(*args, **kwargs)
def remove_option(*args, **kwargs):
    """Historical remove_option"""
    warnings.warn(
        "Accessing configuration method 'remove_option' directly from the configuration module is "
        "deprecated. Please access the configuration from the 'configuration.conf' object via "
        "'conf.remove_option'",
        DeprecationWarning,
        stacklevel=2,
    )
    return conf.remove_option(*args, **kwargs)
def as_dict(*args, **kwargs):