Fixes home-assistant/core#97440
Previously starkvind exposed 10 speed settings and no modes, where 10% corresponded to auto mode
and 20%-100% corresponded to fixed speeds.

This patch correctly exposes auto mode as a mode. It also adds support for showing the actual
fan speed while auto mode is enabled.
Starkvind supports 9 fan speeds. Because 9 doesn't neatly fit into 100% I cheated a bit and divided
the 100% into 10% increments, where trying to set the fan to 10% sets it to 20% instead. I believe
that this gives the overall better user experience compared to having 11.11% increments.
The 5 speed modes present on the physical interface of the device correspond to HA speed settings 20%,
40%, 60% and 100%.