EDA_ITEMs are responsible for giving their parent a crack at it if
they failed to resolve it. This recurses all the way up to the schematic/
board, and then to the project.
Cross-reference handling is also move to the EDA_ITEMs. It must be done
before bubbling up so that we don't end up in loops. (The aDepth parameter
will break the loop, but without having done anything useful.)
Fixes https://gitlab.com/kicad/code/kicad/issues/13541