refactor: move llama3 impl to meta_reference provider (#1364)

Just moving bits to a better place

## Test Plan

```bash
torchrun $CONDA_PREFIX/bin/pytest -s -v test_text_inference.py
```

llama_stack/providers/inline/inference/meta_reference/generation.py

@@ -39,12 +39,7 @@ from llama_stack.models.llama.datatypes import (
     SamplingParams,
     TopPSamplingStrategy,
 )
-from llama_stack.models.llama.llama3.args import ModelArgs
 from llama_stack.models.llama.llama3.chat_format import ChatFormat, LLMInput
-from llama_stack.models.llama.llama3.model import Transformer
-from llama_stack.models.llama.llama3.multimodal.model import (
-    CrossAttentionTransformer,
-)
 from llama_stack.models.llama.llama3.tokenizer import Tokenizer
 from llama_stack.models.llama.sku_list import resolve_model
 from llama_stack.providers.utils.inference.prompt_adapter import (
@@ -53,6 +48,9 @@ from llama_stack.providers.utils.inference.prompt_adapter import (
 )
 
 from .config import MetaReferenceInferenceConfig, MetaReferenceQuantizedInferenceConfig
+from .llama3.args import ModelArgs
+from .llama3.model import Transformer
+from .llama3.multimodal.model import CrossAttentionTransformer
 
 log = logging.getLogger(__name__)
 

llama_stack/providers/inline/inference/meta_reference/quantization/loader.py

@@ -20,10 +20,10 @@ from torchao.quantization.GPTQ import Int8DynActInt4WeightLinear
 
 from llama_stack.apis.inference import QuantizationType
 from llama_stack.models.llama.datatypes import CheckpointQuantizationFormat
-from llama_stack.models.llama.llama3.args import ModelArgs
-from llama_stack.models.llama.llama3.model import Transformer, TransformerBlock
 from llama_stack.models.llama.sku_list import resolve_model
 
+from ...llama3.args import ModelArgs
+from ...llama3.model import Transformer, TransformerBlock
 from ..config import MetaReferenceQuantizedInferenceConfig
 
 log = logging.getLogger(__name__)

llama_stack/providers/inline/inference/meta_reference/quantization/scripts/quantize_checkpoint.py

@@ -24,9 +24,9 @@ from fairscale.nn.model_parallel.initialize import (
 )
 from torch.nn.parameter import Parameter
 
-from llama_stack.models.llama.llama3.args import ModelArgs
-from llama_stack.models.llama.llama3.model import Transformer, TransformerBlock
 from llama_stack.models.llama.llama3.tokenizer import Tokenizer
+from llama_stack.providers.inline.inference.meta_reference.llama3.args import ModelArgs
+from llama_stack.providers.inline.inference.meta_reference.llama3.model import Transformer, TransformerBlock
 from llama_stack.providers.inline.inference.meta_reference.quantization.fp8_impls import (
     quantize_fp8,
 )