add fake-is-sensor daemon, test loop at startup

[untzag]

I was testing loop at startup, I think there is an issue calling measure without passing self._loop (defaults to False and exits loop):
https://gitlab.com/yaq/yaq-python/-/blob/master/yaqd-core/yaqd_core/_has_measure_trigger.py#L56

I was wrong about the issue, but current behavior for me is loop exits before running _measure once.

Update: my issue was unrelated to the core module (my daemon init called measure without passing loop bool, which killed looping)