Use Kelvin as the preferred color temperature unit

**Describe the problem you have/What new integration you would like**
When communicating with Home Assistant through the `api` component, communication should be done in kelvin rather than mireds.

**Please describe your use case for this integration and alternatives you've tried:**
The maximum temperature of my device is 6500 kelvin, but I can only set it as high as 6493 kelvin due to unit conversion.

The same issue occurs for the lower bounds. The minimum for this device is 2700, however I can only set it as low as 2702 kelvin.

In addition, there's this frustrating visual effect when setting the temperature as a result of unit conversion.
[Screencast from 03-20-2023 08:24:30 PM.webm](https://user-images.githubusercontent.com/92653912/226520472-c3c00698-6bfe-4e76-8acc-7937f6941631.webm)

There are no alternatives to be tried other than simply not using ESPHome since mireds are the only unit used in communication with Home Assistant.

**Additional context**