exponential_dc_gain not exposed in LFFEMAnalogOutputPort: filter DC gain always defaults to 1

[fabrizioberr]

The parameter "exponential_dc_gain" for the Output Filter is missing in analog_outputs. As a result, when using an exponential output filter intended for high-pass filter correction, the DC gain cannot be changed and is always 1.

Suggested fix by lukaspahl

class LFFEMAnalogOutputPort(LFAnalogOutputPort, FEMPort):
    fem_type: ClassVar[str] = "LF"
    sampling_rate: float = 1e9  # Either 1e9 or 2e9
    upsampling_mode: Literal["mw", "pulse"] = "mw"
    exponential_filter: Optional[List[Tuple[float, float]]] = None
    exponential_dc_gain: float = 1 #This line is new
...

and

def get_port_properties(self) -> Dict[str, Any]:
        port_properties = super().get_port_properties()
        if self.exponential_filter is not None:
            filter_properties = port_properties.setdefault("filter", {})
            filter_properties["exponential"] = list(self.exponential_filter)
            filter_properties["exponential_dc_gain"] = self.exponential_dc_gain #This line is new
...