**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
self._validate_config_dependencies()
        for section, replacement in self.deprecated_values.items():
            for name, info in replacement.items():
                old, new, version = info
                current_value = self.get(section, name, fallback=None)
                if self._using_old_value(old, current_value):
                    new_value = re.sub(old, new, current_value)
                    self._update_env_var(section=section, name=name, new_value=new_value)
                    self._create_future_warning(
                        name=name,
                        section=section,
                        current_value=current_value,
                        new_value=new_value,
                        version=version,
                    )
        self.is_validated = True
    def _validate_config_dependencies(self):
        """
        Validate that config values aren't invalid given other config values
        or system-level limitations and requirements.
        """
        is_executor_without_sqlite_support = self.get("core", "executor") not in (
            'DebugExecutor',
            'SequentialExecutor',
        )
        is_sqlite = "sqlite" in self.get('core', 'sql_alchemy_conn')
        if is_sqlite and is_executor_without_sqlite_support:
            raise AirflowConfigException(f"error: cannot use sqlite with the {self.get('core', 'executor')}")