v20.0.0 - TypeScript, React, Jest, and more

New configs

• hardcore/ts
• hardcore/react
• hardcore/react-testing-library
• hardcore/jest

Major changes

hardcore/ts-for-js

Use ESLint core rules instead of @typescript-eslint/* extension rules (extension rules don't have any benefits over ESLint core rules when linting JavaScript).

Other changes

• Add unicorn/prefer-object-from-entries
• Add unicorn/no-useless-length-check
• Add unicorn/no-useless-spread