Avoid encoding test-data as strings, since this exceeds MSVC limits
on string literals, and tests don’t need to be relocatable anyway,
so we can just hard-code the source location into config.h
Re-work how position-init and ATC-manager work together to do
parking assignment and fallback (when the parking is unavailable).
Improve the logic for the reposition case, and teach ATC-manager about
reposition explicitly.
When the parking is unavailable, explicitly fall back to best-runway
selection in finalizePosition.
Add many additional position-init tests, to cover all of this.
