improve test coverage of new `check_restrictions`

[JounQin]

It's concerning that these new check_restrictions calls are not covered by tests. I doubt they are aligned to enhanced-resolve?

The tests are same as https://github.com/webpack/enhanced-resolve/blob/main/test/restrictions.test.js

I meant we probably need more tests to cover these new checks, to avoid regressions in the future. I try to make all code paths covered by tests.

Originally posted by @Boshen in #604 (comment)