Enable a couple of additional `eslint-plugin-unicorn` rules

- `no-useless-collection-argument` which required no code changes, see https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/no-useless-collection-argument.md
 - `prefer-classlist-toggle` which required one change (done automatically with `gulp lint --fix`), see https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-classlist-toggle.md