Geometry Nodes: UV tangent node

This node outputs tangent values for face corners. There are two methods:
- **Exact** is the same MikkTSpace calculation used elsewhere in Blender.
- **Fast** (from #131308) is over 4x faster, and useful in many of
  the same situations, though not necessarily tangential to the surface.

The reason to include both methods is that there are use cases where the
quality of the tangents don't matter (though the results are actually very
similar visually), we just need some continuous values across faces.

Pull Request: https://projects.blender.org/blender/blender/pulls/145813

scripts/startup/bl_ui/node_add_menu_geometry.py

@@ -846,6 +846,7 @@ class NODE_MT_gn_mesh_uv_base(node_add_menu.NodeMenu):
     def draw(self, _context):
         layout = self.layout
         self.node_operator(layout, "GeometryNodeUVPackIslands")
+        self.node_operator(layout, "GeometryNodeUVTangent")
         self.node_operator(layout, "GeometryNodeUVUnwrap")
 
         self.draw_assets_for_catalog(layout, self.menu_path)