Update power plant related preset

[skyper]

I split this of #21396 where plant:method is one part.
I see some possible improvements:

• add icons to values of plant:source using the icons for generator:source
  • changing the combo into a multiselect?
• add power:method
  • This probably leads to own presets per plant:source as only some methods are valid for each source
    • Do we find different icons and/or should we use different background colors per source?

• add new preset for ​power=heliostat

Some validator warnings might be useful, see #