Geometry Nodes: support Noise Texture node

This makes the Noise Texture node available in geometry nodes.
It should behave the same as in shader node, with the exception
that it does not have an implicit position input yet. That will
be added separately.

Differential Revision: https://developer.blender.org/D12467

source/blender/functions/FN_multi_function_params.hh

@@ -272,6 +272,22 @@ class MFParams {
     return span;
   }
 
+  /**
+   * Same as #uninitialized_single_output, but returns an empty span when the output is not
+   * required.
+   */
+  template<typename T>
+  MutableSpan<T> uninitialized_single_output_if_required(int param_index, StringRef name = "")
+  {
+    return this->uninitialized_single_output_if_required(param_index, name).typed<T>();
+  }
+  GMutableSpan uninitialized_single_output_if_required(int param_index, StringRef name = "")
+  {
+    this->assert_correct_param(param_index, name, MFParamType::SingleOutput);
+    int data_index = builder_->signature_->data_index(param_index);
+    return builder_->mutable_spans_[data_index];
+  }
+
   template<typename T>
   const VVectorArray<T> &readonly_vector_input(int param_index, StringRef name = "")
   {