fix(eslint-plugin): [no-var-requires] report when used in type assertion

[armano2]

This fixes issue with no-var-requires not reporting issues for <Foo>require('./foo.json');

i found this issue while doing https://github.com/typescript-eslint/typescript-eslint/pull/3005/files#r571368246

[typescript-eslint]

Thanks for the PR, @armano2!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

---

🙏 Please, if you or your company is finding typescript-eslint valuable, help us sustain the project by sponsoring it transparently on https://opencollective.com/typescript-eslint. As a thank you, your profile/company logo will be added to our main README which receives thousands of unique visitors per day.