chore: move all Llama Stack types from llama-models to llama-stack (#1098)

llama-models should have extremely minimal cruft. Its sole purpose
should be didactic -- show the simplest implementation of the llama
models and document the prompt formats, etc.

This PR is the complement to
https://github.com/meta-llama/llama-models/pull/279

## Test Plan

Ensure all `llama` CLI `model` sub-commands work:

```bash
llama model list
llama model download --model-id ...
llama model prompt-format -m ...
```

Ran tests:
```bash
cd tests/client-sdk
LLAMA_STACK_CONFIG=fireworks pytest -s -v inference/
LLAMA_STACK_CONFIG=fireworks pytest -s -v vector_io/
LLAMA_STACK_CONFIG=fireworks pytest -s -v agents/
```

Create a fresh venv `uv venv && source .venv/bin/activate` and run
`llama stack build --template fireworks --image-type venv` followed by
`llama stack run together --image-type venv` <-- the server runs

Also checked that the OpenAPI generator can run and there is no change
in the generated files as a result.

```bash
cd docs/openapi_generator
sh run_openapi_generator.sh
```

llama_stack/scripts/generate_prompt_format.py

@@ -0,0 +1,65 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# top-level folder for each specific model found within the models/ directory at
+# the top-level of this source tree.
+
+import importlib
+from pathlib import Path
+from typing import Optional
+
+import fire
+
+# from llama_stack.models.llama.datatypes import *  # noqa: F403
+from llama_models.llama3.reference_impl.generation import Llama
+
+THIS_DIR = Path(__file__).parent.resolve()
+
+
+def run_main(
+    ckpt_dir: str,
+    module_name: str,
+    output_path: str,
+    model_parallel_size: Optional[int] = None,
+):
+    module = importlib.import_module(module_name)
+    assert hasattr(module, "usecases"), f"Module {module_name} missing usecases function"
+    tokenizer_path = str(THIS_DIR.parent / "llama3/api/tokenizer.model")
+    generator = Llama.build(
+        ckpt_dir=ckpt_dir,
+        tokenizer_path=tokenizer_path,
+        max_seq_len=512,
+        max_batch_size=1,
+        model_parallel_size=model_parallel_size,
+    )
+
+    use_cases = module.usecases()
+    text = ""
+    for u in use_cases:
+        if isinstance(u, str):
+            use_case_text = f"\n{u}\n"
+        else:
+            use_case_text = u.to_text(generator)
+
+        text += use_case_text
+        print(use_case_text)
+
+    text += "Thank You!\n"
+
+    with open(output_path, "w") as f:
+        f.write(text)
+
+
+def main():
+    fire.Fire(run_main)
+
+
+if __name__ == "__main__":
+    main()