The previous version of the boundary check was a quick heuristic where
we compared the bounding box of the design to that of the prBoundary layer.
Over time we came across some designs where this is insufficient.
The new check compares the bounding box to the correct project size
based on the .def template and verifies that there is a rectangle of
this exact size in the prBoundary layer at the top level.
The patch also abstracts parsing the .def template into a separate
function since we now use it in two different checks.
The flag enables a second power supply (VAPWR), not necessarily 3.3V (gf180's core is already 3v3), so "uses_3v3" no longer accurately describes its purpose.
Rename it across project_info, precheck, project and shuttle, and update the validation message accordingly.
The legacy "uses_3v3" key is still accepted when reading info.yaml, so existing project configs keep working.
htfab