**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
for (source_name, config) in configs:
            for section in config.sections():
                AirflowConfigParser._replace_section_config_with_display_sources(
                    config, config_sources, display_source, raw, section, source_name
                )
    @staticmethod
    def _replace_section_config_with_display_sources(