hclwrite: Fix NewExpressionAbsTraversal signature
hclwrite: Fix NewExpressionAbsTraversal signature

It is still not implemented, but at least now it is declared with the
correct return type.

hashicorp/hcl,strivecast/hcl,strivecast/hcl,hashicorp/hcl,hashicorp/hcl,hashicorp/hcl,strivecast/hcl,hashicorp/hcl,strivecast/hcl,strivecast/hcl