Temperature data should have its unit configurable

[rafaellehmkuhl]

The main use-case is the water temperature VGI. It should be easy to change between Celsius and Fahrenheit.

[ES-Alexander]

Raised again and discussed somewhat in this forum thread.

@dgudiel has also mentioned it's likely important for some of our US-based users, and a non-arcane process for it is a high priority for when (or ideally before) Cockpit becomes the officially recommended GCS for BR ROVs.

[ES-Alexander]

I feel like a decent way of approaching this would be to:

1. #2073
2. Create a (built in) string compound variable called UNITS/temperature = {{ UNITS/displayPreference }} == "metric" ? "℃" : "℉"
3. Create the following numerical compound variables:
   • Temperature Celsius = {{ SCALED_PRESSURE2/temperature }} / 100
   • Temperature Fahrenheit = {{ temperature-celsius }} * 1.8 + 32
   • Temperature = {{ UNITS/displayPreference }} == "metric" ? {{ temperature-celsius }} : {{ temperature-fahrenheit }}
4. Allow using string data-lake values in the units of VeryGenericIndicator widgets
5. Re-implement the water temperature preset as using {{ temperature }} and {{ UNITS/temperature }}