Output configuration follow-ups

Some things that can and should be done after !4431 (merged) is merged:

• with setting storage being kwin-internal, expose better user-facing transforms to libkscreen - that is, make "90° rotated" be "normal" on the Steam Deck (and obv apply that to all devices with a panel orientation property)
• make auto rotation take panel orientation into account
• reposition other screens when auto rotation is used
• when a new output setup is discovered, take the closest existing setup into account. For example, when you add a third output to an existing two-output setup, append it to the right instead of generating a completely new setup