How do we deal with devices that need configuration to initialise

[DominicOram]

Currently the ApertureScatterguard and the Eiger devices need to be passed a set of parameters to be valid devices. This is done by doing something like the following:

def eiger(params: Optional[Parameters] = None):
    eiger = EigerDetector(...)
    if params is not None:
        eiger.set_params(params)
    return eiger

This causes issues as it's easy to make an invalid Eiger that has no parameters. Instead it would be nicer to do one of the following:

1. Require parameters to be set when instantiating the device - this then make it very hard to easily create all devices on the beamline
2. Have some method of getting a good default set of parameters - this opens up cans of worms around proper storage of configurations. e.g. do we have a configuration service that dodal will interrogate when trying to initialise a device?

[stan-dot]

relevant to #483

thoughts @coretl , @DominicOram ?