Geometry Nodes: Edges to Face Groups Node

Add a new node that groups faces inside of boundary edge regions.
This is the opposite action as the existing "Face Group Boundaries" node[1].
It's also the same as some of the "Initialize Face Sets" options in sculpt mode [2].

Discussion in T102962 has favored "Group" for a name for these
sockets rather than "Set", so that is used here.

[1]: https://docs.blender.org/manual/en/3.4/modeling/geometry_nodes/mesh/face_set_boundaries.html
[2]: https://docs.blender.org/manual/en/3.5/sculpt_paint/sculpting/editing/face_sets.html#initialize-face-sets

@@ -53,6 +53,7 @@ void register_geometry_nodes()
   register_node_type_geo_edge_paths_to_curves();
   register_node_type_geo_edge_paths_to_selection();
   register_node_type_geo_edge_split();
+  register_node_type_geoedges_to_face_groups();

@@ -0,0 +45,4 @@
+    const Span<MPoly> polys = mesh.polys();
+    const Span<MLoop> loops = mesh.loops();
+
+    /* Create Edge/Face Lookup */

@@ -0,0 +50,4 @@
+        polys, loops, mesh.totedge);
+
+    /* Join faces based on edge values */
+    DisjointSet<int> islands(polys.size());

@@ -0,0 +53,4 @@
+    DisjointSet<int> islands(polys.size());
+    for (const int edge_i : non_boundary_edges) {
+      for (const int a : edge_to_face_map[edge_i]) {
+        for (const int b : edge_to_face_map[edge_i]) {

@@ -0,0 +61,4 @@
+
+    /* Output faces final assigned groups */
+    Array<int> output(domain == ATTR_DOMAIN_FACE ? mask.min_array_size() : polys.size());
+    VectorSet<int> ordered_roots;

@@ -0,0 +65,4 @@
+    const IndexMask poly_mask = domain == ATTR_DOMAIN_FACE ? mask : polys.index_range();
+    for (const int poly_i : poly_mask) {
+      const int64_t root = islands.find_root(poly_i);
+      output[poly_i] = ordered_roots.index_of_or_add(root);

@@ -0,0 +26,4 @@
+{
+  for (const int i : indices.index_range()) {
+    for (int j = i + 1; j < indices.size(); j++) {
+      set.join(i, j);