White support on google assistant via hass with RGBW

**Describe the problem you have/What new integration you would like**
I'm not sure if this lands on esphome or if it is a home-assistant question (hass not presenting the correct options to google?)

When using RGBW lights, asking google to set the lights to white turns on all of the RGB bulbs. I can't find a way to trigger the white only LED. I would have thought asking google to set the lights to white would disable RGB and turn on the white LED, asking google to set the lights to red would disable the white LED and turn on the red LED, etc.

This gets more complex with RGB WW/CW of course, but there could be warm white & cool white voice triggers.

Currently having an RGBW bulb seems kind of pointless as it only controls the RGB portion, I've changed my lights to monochromatic white only to make them suitable for daily use and ignored the RGB portion.

**Please describe your use case for this integration and alternatives you've tried:**
Use case is to make RGBW bulbs more end user friendly.

An alternative I have tried is adding the white light as monochromatic and the RGB bulbs as RGB, this presents 2 separate entities in home-assistant which is not ideal but they can be controlled independently, when you sync them to google assistant it wants to group lights which makes changing options difficult.

The issue names no repository files, tests, or entry points. First determine whether RGBW-to-white behavior belongs in ESPHome, Home Assistant, or Google Assistant, then trace how RGBW entities are exposed and controlled; done means voice commands select the white, RGB, warm-white, or cool-white channels appropriately.

Written by the indexing model from the issue text.