Fix plugin init script
Add ROCm __init__.py to plugin wheel sources
Include jax_plugins/rocm/__init__.py in the wheel_sources static_srcs
so it can be copied during the wheel build process. This file contains
critical ROCm initialization logic including:
- ROCm path configuration (bitcode, linker)
- AMD GPU detection via KFD
- Shared memory size validation for multi-GPU setups
Fixes build error where build_gpu_kernels_wheel.py couldn't find the
__init__.py file to copy into the plugin wheel.
