Migrate to new ESLint flat configuration format

[haines]

• Support eslint v9 import-js/eslint-plugin-import#2948
• [Feature Request] Support new ESLint flat config import-js/eslint-plugin-import#2556
• eslint-plugin-react-hooks: Add support for ESLint v9 facebook/react#28773
• eslint-plugin-react-hooks & "Flat Config" (ESLint 9) facebook/react#28313
• eslint-plugin-tsdoc