Adds the four missing overloads (value + predicate × WaitAsync + WaitForAsync)
to CompileAttributeAccessor so template/call scripts that use Attributes.WaitAsync
or Attributes.WaitForAsync pass design-time Roslyn validation. Covers both root
scope and composed/child scope (Children["x"].Attributes.WaitAsync) automatically
since CompileCompositionAccessor.Attributes already returns CompileAttributeAccessor.