Gemma 2 LoRA support

[Aquasar11]

Please add Gemma 2 9b LoRA support. I have tried to build the Tensorrt-llm engine, and when I set the --lora_plugin auto or any other type, it gives me this error

Traceback (most recent call last):
  File "/usr/local/bin/trtllm-build", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/commands/build.py", line 602, in main
    parallel_build(model_config, ckpt_dir, build_config, args.output_dir,
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/commands/build.py", line 425, in parallel_build
    passed = build_and_save(rank, rank % workers, ckpt_dir,
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/commands/build.py", line 390, in build_and_save
    engine = build_model(build_config,
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/commands/build.py", line 383, in build_model
    return build(model, build_config)
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/builder.py", line 1096, in build
    model = optimize_model_with_config(model, build_config)
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/builder.py", line 828, in optimize_model_with_config
    model.use_lora(build_config.lora_config)
  File "/usr/local/lib/python3.10/dist-packages/tensorrt_llm/top_model_mixin.py", line 54, in use_lora
    raise NotImplementedError("Subclass shall override this")
NotImplementedError: Subclass shall override this