Geometry Nodes: Update boilerplate code for attributes

Merge branch 'geometry-nodes' into geometry-nodes-attribute-nodes

Merge branch 'master' into geometry-nodes

Geometry Nodes: simplify GeometrySet ownership handling

Previously, GeometrySets and GeometryComponents has reference
counters and could be shared. This commit changes it so that
only GeometryComponents are shared. A GeometrySet is a fairly
small type that is cheap to copy.

A lot of code simplifies when we can assume that GeometrySet
is cheap to copy.

Geometry Nodes: Move GeometrySet classes to global namespace

Brecht and I decided to move the GeometrySet classes
to the global namespace for now. This way we can use
the same type in C and C++ and don't have to use
reinterpret_cast as often.

Merge branch 'master' into geometry-nodes

Geometry Nodes: Improve node group output modifier error

More than output for the modifier's node group is fine, because the
node group may be used in other situations, but the modifier will
not work if there is no geometry output socket.

Merge branch 'master' into geometry-nodes

Empty Modifier: Fix build and put in the right order

Bypassing the macro that creates modifiers to allow the enum to be
referring to the Empty modifier, but the internal struct in the code to
be Nodes.

Also fix the name of the new created modifiers to be "Empty".

Fix was built with rBb458ea6b23381a9acb90dbbd73ced678e1d404c5.

Rename: "Nodes" modifier to "Empty" (take 2)

Leave the internal DNA data struct as "Nodes", and only rename the
modifier and user interface to Empty.

See 4a2734a835c10d5bffaaceddc59c for the original take and the reasoning
for renaming from Nodes to Empty.

Revert "Rename: "Nodes" modifier to "Empty""

This reverts commit 4a2734a835c10d5bffaaceddc59c41837801f402.

Reverting this so that all we change is the UI name, not the DNA struct
and the internal variable names.

Geometry Nodes : Removing "Combine Strings" and Group Instance ID from UI

This diff remove "Combine Strings" and "Group Instance ID" nodes from the UI (but keep them in the source code to be able to bring them back if needed).

This is part of "Cleanup 1st Sprint Nodes" (https://developer.blender.org/T82370).

Differential Revision: https://developer.blender.org/D9558

Rename: "Nodes" modifier to "Empty"

This introduces a regression. Users need to re-create their modifiers
and set their values again. The NodeGroups are intact so all they need
is to create new "Empty" modifiers and set the node group.

---

Original problem: Eventually most modifiers will be node-based, so naming
this new modifier "Nodes" will get outdated pretty quickly.

Calling it "Empty" it's fairly descriptive, since the node tree simply connects
the modifier Input to an Output, without any effect.

There is a potential problem, that it could be associated with the
Empty object type. Like some sort of Hook.

This is the task T82700, and the design task T82537.

Geometry Nodes: Improve error messages for property mismatches

Related to T82438. This adds some basic checks for common errors and
currently unsupported socket types in the modifier.

Merge branch 'master' into geometry-nodes

Cleanup: Remove unused variable

Cleanup: Clang Tidy

Cleanup: Spelling

Also move some input extraction after the special case check.

Geometry Nodes: Add method enums to mesh triangulate node

This commit adds the remaining "method" enums from the triangulate modifier.

Differential Revision: https://developer.blender.org/D9502

Merge branch 'master' into geometry-nodes