Allow saving "within" to variable for rule "Suggest using screen while querying (testing-library/prefer-screen-queries)"

According to the rule using

```ts
within(screen.getByTestId('section')).getByText('foo');
```
is allowed.

However, saving the result to a variable 

```ts
const context = within(screen.getByTestId('section')).getByText('foo');
```

to re-use it, results in the warning.