Added availability topic in HA as V1 devices report state every
4 hours at most, and V2 devices report every 2 hours at most.
Added a state file that gets saved on shutdown and sensor reload.
This file saves the last seen timestamp and online state for each
sensor so that it has consistancy across reboots. This file also
contains the shutdown timestamp so that we can ignore stale state
data in case the service is shut down for a long time, or if the
service crashes and a fresh state file is not written. If the state
data is stale, the service will just start fresh assuming all devices
are online.

Added timeout setting for sensors to configure a timeout per device
if desired. Otherwise it'll default to 4 hours for V2 devices and
8 hours for V1 and unknown devices. This is twice the max status
period to allow for one missed status update.

Also added a global availability topic that is set online when the
service is running. Both the global availability and the per device
availability must be set to online for a device to be available.

Switched mqtt connection method so it connects faster and availability
topics are sent after the connection is active rather than before.
This also allows the main thread to loop and check availability of
the sensors.

The main loop also checks communication with the dongle, by getting
the mac address, which allows us to close and reopen the dongle if
we lose communication with the device. This is an issue I've been
dealing with for a long time.

Fixed shutdown by sending the correct signal in the service file
and properly handling it in shutdown. Wait for dongle loop to finish
before closing the fd.

Updated logging. Set the sample logging conf to INFO instead of DEBUG
and updated log messages to primarily log mqtt messages/events, etc
at this level. Passing in LOGGER to the dongle class so logs from the
dongle show up in the log file.

Fix packet parsing to not throw away partial packets which can be
parsed correctly when the rest of the message is received.

Fix new device scan to add the device even if the additional calls
timeout, as long as we got a result from the scan.

Fix automatic device adding for already linked devices to default
the class to opening instead of None. This means even motion sensors
will be initially added as a contact sensor, but should get fixed when
the sensors.yaml configuration is updated.

Signed-off-by: Nathan Bahr <[email protected]>

Fixed logging in bridge tool cli.
Added some comments and logs to dongle functions.
Increased default timeout for getting sensor list and verifying sensor.
FIxed a few spots where the incorrect mac was used.
Re-added last_seen attribute so that it's updated if the device is
still reporting but hasn't had a state change.
Removed the dongle get mac check. I was still having problems with
my dongle "hanging" every once in a while, not receiving any updates.
I happened to have a second dongle so I switched to that and so far it
has been much more stable. I used to get semi-frequent errors about
mismatched checksums that are much more rare now as well.