Enhance display/waveshare_epaper component with support for 2bit grayscale on supported 7.5inch display

[cromelex]

Component name

display/waveshare_epaper

Link to component documentation on our website

https://esphome.io/components/display/waveshare_epaper/

Describe the enhancement

The waveshare_epaper component as it works today seems to allow only allow B/W rendering on displays such as the 7.50inV2 and 7.50inV2p, in my understanding due to memory limitations.

This type of display is being used by the folks at TRMNL, and someone has done an implementation that allows 2 bit grayscale to be displayed on these epapers.

usetrmnl/trmnl-firmware#201

If someone could potentially "port" this into ESPHome, it would probably be an interesting improvement over the existing functionality

Use cases

Grayscale with 4 or 8 colours would potentially allow an epaper display to be much more useful for displaying Home Assistant information or dashboards (via online_image component).

Anything else?

No response