Deprecate sensors/data API endpoints to require the entity address

[nhoening]

The sensor ID should be enough, like with all other endpoints. We might be able to retire entity addresses completely after sunsetting this feature.

The whole ¸SensorField part of our schemas, where an entity address is (de)serialized, is only used twice - in the GET and POST endpoint for sensor data.

class SensorField(fields.Str):
    """Field that de-serializes to a Sensor,
    and serializes a Sensor into an entity address (string).
    """

This should not be used anymore. First, we should deprecate the field in both endpoints, and add the SensorIDField as another option to use. We should document only that option in the endpoint docstring.

Remember our strategy for deprecating things: https://flexmeasures.readthedocs.io/en/latest/api/introduction.html#deprecation-and-sunset