Change default idle attribute to false

Right now when the companion app is started, the status sensor will have the
`idle` attribute set to `unknown` until the computer has been put in suspend
or is shut down. I'm suggesting that we change the default value to `false`
instead, because unless I'm mistaken, it should be safe to assume that the
computer is _not_ idle when the companion app starts. Having only two valid
states of the `idle` attribute simplifies using it in e.g. automations.

halinuxcompanion/sensors/status.py

@@ -16,7 +16,7 @@
 Status.icon = "mdi:cpu-64-bit"
 
 Status.state = True
-Status.attributes = {"reason": "power_on", "idle": "unknown"}
+Status.attributes = {"reason": "power_on", "idle": "false"}
 
 IDLE = {True: {"idle": "true"}, False: {"idle": "false"}}
 SLEEP = {True: {"reason": "sleep"}, False: {"reason": "wake"}}