Change PBVH normal calculation to also update vertices connected to
vertices with an update tag. This is necessary because vertex normals
are the mixed face normals, so changing any face's normal will change
the normals of all connected faces.
This change requires that the PBVH always have a vertex to face
topology map available. In the future this will likely be cached on
meshes though, which will reduce the delay it adds when entering sculpt
mode.
Now, first all face normals are updated, then the normals for
connected vertices are mixed from the face normals. This is a
significant simplification to the whole process, which previously
worked with atomics and normals at the triangle level. Similar changes
changes for regular non-sculpt normal calculation are being worked on
in #105920.
Pull Request: https://projects.blender.org/blender/blender/pulls/107458
ac02f94caf