Respect pressure units

[warmsound]

JMart26 has set pressure units on watch to inHg, but pressure remains in mbar.

As per this forum post, there is no CIQ access to the pressure units on watches that support the setting, so the options become:

1. Use an existing units setting (e.g. temperature/altitude) to set pressure units (as suggested here);
2. Provide in-app setting.

2 may be more reliable, as there is no guarantee that e.g. temperature and pressure will both use the same kind (statue/metric) of units.