Add some tests for non-identifiers in export/imports

[wooorm]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and couldn’t find anything (or linked relevant results below)

Affected packages and versions

all, probably

Link to runnable example

No response

Steps to reproduce

import { 'alpha-bravo' as charlieDelta } from 'echo'
export { 'foxtrot-golf' as 'hotel-india' } from 'juliet'

Expected behavior

should work, somehow, probably.

Actual behavior

davidbonnet/astring#713

Runtime

No response

Package manager

No response

OS

No response

Build and bundle tools

No response

[wooorm]

I confirmed on the playground that this now compiles to the broken code:

import {undefined as charlieDelta} from 'echo';
export {undefined} from 'juliet';

…due to the astring bug