Use ESLint flat configurations

[dotNomad]

ESLint v9.0.0 (which is currently in beta.1) will make the eslint.config.js configuration format the default and deprecate the current configuration method. In ESLint 10 our current configuration will no longer be supported.

Note that we cannot use ESLint v9 directly because the typescript-eslint/typescript-eslint#8211 just yet, but can use the configuration format since it is supported in v8 (as long as our extends support it too).

See #1030 for more comments about this as things were figured out.

References

• ESLint 9.0 migration doc

[dotNomad]

eslint-plugin-vue just added support for the flat config: vuejs/eslint-plugin-vue#1291

[dotNomad]

This is no longer on hold - we do not need the Cypress ESLint plugin, and typescript-eslint is all good!