Add support for different number format

[sheaur]

Enhancement Summary

Support for different number format

Detailed Description

I'd like the card to display a comma instead of a point for values like "20.5°C".
Maybe add a config option "decimal_separator" or even better add the possibility to specify a locale.

Additional Context

No response

[edwardtfn]

Locale is quite complex in this context, as all the info provided by HA to ESPHome is not supporting localization and ESPHome itself is quite limited on that.
But we do have an option on the blueprint to select decimal separator. I'm not 100% that was released, but I think so.
Is there a specific location where you are seen this issue?