This commit removes the implicit conversion from points to a mesh
that used to happen before the next modifier. It also removes the
implicit realizing of instances that happened before another modifier.
Now we have specific nodes for both of these operations, the implicit
conversions make less sense, and implicit instance realizing has already
been removed in other nodes.
Versioning
This commit adds another geometry nodes modifier before modifiers
that would have realized instances implicitly before. The way this works
is currently a bit sketchy, and needs more testing.

