movement: add thermistor readout face

movement/watch_faces/thermistor/thermistor_driver.h

@@ -0,0 +1,13 @@
+#ifndef THERMISTOR_DRIVER_H_
+#define THERMISTOR_DRIVER_H_
+
+// NOTE: This implementation is specific to one prototype sensor board, OSO-MISC-21-009, but both
+// the sensor board design and this implementation are likely to change. Thermistor functionality
+// may even end up being baked into the Sensor Watch library. This is all by way of saying this
+// code is very temporary and the thermistor screens will likely get a rewrite in the future.
+
+void thermistor_driver_enable();
+void thermistor_driver_disable();
+float thermistor_driver_get_temperature();
+
+#endif // THERMISTOR_DRIVER_H_