A sheetpath is required to correctly resolve text variables.
Depending on currentSheet is rife with bugs.
There are many places where we do *not* want to be prepending
field names to the field values, such as netlisting,
building PDF hypertext menus, etc.
Also, Find/Replace needs to work on unresolved text, as
that's what we're going to display (and if replace nuked
your variable references you wouldn't be happy).
(cherry picked from commit b41d446f58)
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
CHANGED: The text variable ${SHEETNAME} now always represents the name of the
sheet when used anywhere in the schematic editor, including the title block
ADDED: A new text variable ${SHEETPATH} which is replaced with the path to the
current sheet - e.g. "/Sheet 1/Sheet 2".
To ensure backward compatibility, the default drawing sheet now uses
${SHEETPATH}. Custom drawing sheets will need to be manually edited.