Preserve more information for CONST values

[dumconstantin]

The AST for operations includes only the reference for a certain value:

{
  "name": {
      "type": "UPDATE",
      "path": [{ type: "CONST", value: foo}, { type: "CONST", value: "bar"]
   }
}

When using variables the name is not preserved and cannot be used later when in debug mode for example:
Update<[foo].bar>

as such the ast should change:

type: "CONST", value: { type: "VARIABLE", name: "foo", ref: foo }
type: "CONST", value: { type: "STRING", value: "foo" }