Configure [`importsNotUsedAsValues`](https://www.typescriptlang.org/tsconfig#importsNotUsedAsValues)
to `error`, and switch from `import` to `import type` where needed.
Also remove the `strict` configuration, as it's inherited from
`@tsconfig/recommended`.
* Extend from the recommended config.
* Remove the exclude field that doesn't contribute to the file
inclusion (include alone should be enough).
* Remove the esModuleInterop field that shouldn't be necessary.