Allow specifying resources in StackRunConfig (#425)

# What does this PR do? 

This PR brings back the facility to not force registration of resources
onto the user. This is not just annoying but actually not feasible
sometimes. For example, you may have a Stack which boots up with private
providers for inference for models A and B. There is no way for the user
to actually know which model is being served by these providers now (to
be able to register it.)

How will this avoid the users needing to do registration? In a follow-up
diff, I will make sure I update the sample run.yaml files so they list
the models served by the distributions explicitly. So when users do
`llama stack build --template <...>` and run it, their distributions
come up with the right set of models they expect.

For self-hosted distributions, it also allows us to have a place to
explicit list the models that need to be served to make the "complete"
stack (including safety, e.g.)

## Test Plan

Started ollama locally with two lightweight models: Llama3.2-3B-Instruct
and Llama-Guard-3-1B.

Updated all the tests including agents. Here's the tests I ran so far:

```bash
pytest -s -v -m "fireworks and llama_3b" test_text_inference.py::TestInference \
  --env FIREWORKS_API_KEY=...

pytest -s -v -m "ollama and llama_3b" test_text_inference.py::TestInference 

pytest -s -v -m ollama test_safety.py

pytest -s -v -m faiss test_memory.py

pytest -s -v -m ollama  test_agents.py \
  --inference-model=Llama3.2-3B-Instruct --safety-model=Llama-Guard-3-1B
```

Found a few bugs here and there pre-existing that these test runs fixed.

llama_stack/providers/tests/resolver.py

@@ -17,29 +17,38 @@ from llama_stack.distribution.build import print_pip_install_help
 from llama_stack.distribution.configure import parse_and_maybe_upgrade_config
 from llama_stack.distribution.distribution import get_provider_registry
 from llama_stack.distribution.request_headers import set_request_provider_data
-from llama_stack.distribution.resolver import resolve_impls
-from llama_stack.distribution.store import CachedDiskDistributionRegistry
-from llama_stack.providers.utils.kvstore import kvstore_impl, SqliteKVStoreConfig
+from llama_stack.distribution.stack import construct_stack
+from llama_stack.providers.utils.kvstore import SqliteKVStoreConfig
 
 
 async def resolve_impls_for_test_v2(
     apis: List[Api],
     providers: Dict[str, List[Provider]],
     provider_data: Optional[Dict[str, Any]] = None,
+    models: Optional[List[Model]] = None,
+    shields: Optional[List[Shield]] = None,
+    memory_banks: Optional[List[MemoryBank]] = None,
+    datasets: Optional[List[Dataset]] = None,
+    scoring_fns: Optional[List[ScoringFn]] = None,
+    eval_tasks: Optional[List[EvalTask]] = None,
 ):
+    sqlite_file = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
     run_config = dict(
         built_at=datetime.now(),
         image_name="test-fixture",
         apis=apis,
         providers=providers,
+        metadata_store=SqliteKVStoreConfig(db_path=sqlite_file.name),
+        models=models or [],
+        shields=shields or [],
+        memory_banks=memory_banks or [],
+        datasets=datasets or [],
+        scoring_fns=scoring_fns or [],
+        eval_tasks=eval_tasks or [],
     )
     run_config = parse_and_maybe_upgrade_config(run_config)
-
-    sqlite_file = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
-    dist_kvstore = await kvstore_impl(SqliteKVStoreConfig(db_path=sqlite_file.name))
-    dist_registry = CachedDiskDistributionRegistry(dist_kvstore)
     try:
-        impls = await resolve_impls(run_config, get_provider_registry(), dist_registry)
+        impls = await construct_stack(run_config)
     except ModuleNotFoundError as e:
         print_pip_install_help(providers)
         raise e