Minimal temperature threshold option

[jerkelens]

Is your feature request related to a problem? Please describe.
I am using multiple Mitsubishi Heavy airconditioners. Currently, through the WF-RAC experimental plugin I am able to get them to work perfectly. I am using simple-thermostat as my go-to card due to its perfect customizability. I can enter a minimal value that's below the device's threshold. It's hard limit is 18 degrees Celsius, through the WF-RAC plugin I am able to set it to 16, which causes an error.

Describe the solution you'd like
I know simple-thermostat is not to blame for this, but since addons make life better, I figured it would come in handy in some cases to provide overrides that limit cosmetic configuration to a certain extent.

Additional context
Thanks for your consideration!