Presenting ... within the result of toString() for both DataFlow::Node and Expr for JavaScript

**Description of the issue**

I tried to retrieve the text presentation of specific `DataFlow::Node` and `Expr`, while the results are all default to abbreviated strings, such as `require('body-parser')` which is supposed to be a `DataFlow::ImportModuleNode` in source code, the result of `toString()` is `require ... arser')`.

[`https://github.com/github/codeql/issues/4811`](https://github.com/github/codeql/issues/4811), this issue had provided a solution of using `getStringValue()` instead of `toString()`, while it seems this solution is only applicable to Literal objects instead of retrieving text presentation of all `DataFlow::Node` and `Expr`.

Is there any proper way to retrieve the full text of nodes and exprs?

Many thanks!