Support for ES2020 arbitrary module namespace identifier names,
which allows using string literals as export/import names.
Examples:
```js
export { foo as "string-name" }
import { "string-name" as foo }
export * as "string-name" from "./mod.js"
```
Before this commit, such objects were printed as `<exception>` because
print() and console.log() had no good way to turn them into strings.
Instead perform the C equivalent of Object.prototype.toString.call(o)
and print the result (which can still error but at least we tried.)
Fixes: https://github.com/quickjs-ng/quickjs/issues/832
Before this commit it segfaulted, now it throws a SyntaxError.
That's still not correct behavior but better than segfaulting.
To be continued.
Includes a small run-test262 fix to handle Windows line endings.
Refs: https://github.com/quickjs-ng/quickjs/issues/567
Saúl Ibarra Corretgé