[unplugin] writeBundle hooks not working in rspack.

### Describe the issue

As described in the support hooks section of unplugin, the writeBundle hook currently receives no arguments when a plugin runs in Rspack.

### Expected behavior

falls back to creating stylex.css if none exist.

### Steps to reproduce

unplugin 2.3.11
@stylexjs/unplugin 0.17.3
@rspack/core 1.6.7

### Test case

_No response_

### Additional comments

_No response_