Put native TS resolver for next config under `--experimental-next-config-strip-types` flag (#84675)
Using Node.js native TS resolution is great. However, enabling by
default can be frustrating for the users as it has restrictions, such as
requiring a file extension for imports, and does not read tsconfig.json
(no import alias).
It also emits a warning when using `next.config.ts` on a CommonJS
project, which is the majority of the apps:
```
(node:68710) [MODULE_TYPELESS_PACKAGE_JSON] Warning: Module type of file:///.../next.config.ts is not specified and it doesn't parse as CommonJS.
Reparsing as ES module because module syntax was detected. This incurs a performance overhead.
To eliminate this warning, add "type": "module" to /.../package.json.
(Use `node --trace-warnings ...` to show where the warning was created)
```
Therefore, put this under an `--experimental-next-config-strip-types`
flag for now.