Health Tracking additions

Sometimes the step count is lost (after a reboot/upgrade)

There is a Bangle.setStepCount function but nobody uses getSteps - they generally use Bangle.getHealthStatus("day") and I'm afraid there is no way to set that at the moment.

Potentially this could be added and then the health app could try and figure out what the current day's step count was at boot time.

... but hopefully full reboots are so rare this isn't a big issue.

And even when it does happen, then step counter may show the wrong step count, but if you go into the health app you'll see that all the steps are still recorded for the day