[Realtime] Wrap sftp configurations to also read from env variables

@timlinux: Please see this to see all the environment variables that we need to pass to the container.
Hi. This comment applies to the impact functions that follow too. It would be good to include a description in the docstrings of what the behaviour will be e.g.:

```python
 """Get base url of the sftp.
 
    If set, the environment variable EQ_SFTP_BASE_URL will be used, otherwise the url will be taken from the configuration file.

     :return: The base URL of the sftp.
     :rtype: str
     """
```