opencl: fold the gpt-oss MoE per-expert bias adds into the epilogue (op/kernel fusion) (#26431)

* opencl: fold the gpt-oss MoE bias adds into swiglu_oai

Default on, opt out with GGML_OPENCL_FUSE_MOE_BIAS_GLU=0.

* opencl: fold the MoE down-projection bias into the combine

Default on, opt out with GGML_OPENCL_FUSE_MOE_BIAS_COMBINE=0.