Project-level auto-fix features that have to be invoked from Runtime classes, so cannot be placed in the .Editor namespaces
public class ValidatorProject
Centralised method for runtime classes to warn about a need for definite upgrade (hard, throws exception / displays popup dialog modal)
FlexItems can exist as orphans; FlexContainers can exist without an ancestor RootFlexContainer; but the
CSS/FlexBox algorithm can only run for FlexItems/FlexContainers that exist in a Unity tree of parented
objects where the topmost object is a RootFlexContainer. This method checks that reality, and when this
method returns false: rendering/layout should be ignored or suspended, since you do NOT have a valid
Flexbox tree to layout.
Unity made this difficult to use, by repeatedly changing their nested-prefab implementation, and
never properly planning the APIs. By trial and error (i.e. this could fail for some edge-cases) this appears to
be correct: it returns true iff the object provided is being edited in prefab view OR is a prefab in the project
BUT NOT an object in the scene.
Centralised method for runtime classes to warn about a need for probable upgrade (soft, console-only)