.resolveSourceFileDependencies does not work as I would expect; no node_modules files

I would expect that the following code (in a file named 'index.ts') would list not only that index.ts file,
but also all files that are included by the import statement (in this case the "ts-morph" import).
This is not the case. This code only lists that 1 index.ts file.
What do I need to do to get the files in node_modules listed?

```ts
import * as tm from "ts-morph"

const project = new tm.Project({
tsConfigFilePath: "./tsconfig.json"
})

const files = project.resolveSourceFileDependencies()

files.forEach(($) => {
console.log($.getFilePath())
})

project.getSourceFiles().forEach(($) => {
console.log(">", $.getFilePath())
})

Start with index.ts, tsconfig.json, and the Project.resolveSourceFileDependencies() call shown in the issue. Run the example and inspect the resulting files alongside project.getSourceFiles(); done means the expected handling of the ts-morph import and node_modules files is established and the behavior or guidance matches that expectation.

Written by the indexing model from the issue text.