fix: ensure resource registration arguments are typed (#1941)

# What does this PR do?

closes https://github.com/meta-llama/llama-stack/issues/1586

this issue arises when loading an mcp_endpoint from run.yaml. the issue
does not manifest for mcp servers added via a running distro server. the
existing tests only cover the case of adding to a running server.

the code for loading run.yaml strips type information from mcp_endpoint,
passing `{"uri": ...}` instead of `URL(uri=...)` along to the resource
provider registration.

## Test Plan
1. run an mcp server
2. add an mcp tool config to the dev.py, e.g.
```
diff --git a/llama_stack/templates/dev/dev.py b/llama_stack/templates/dev/dev.py
index 69924acb..e0dc7189 100644
--- a/llama_stack/templates/dev/dev.py
+++ b/llama_stack/templates/dev/dev.py
@@ -6,6 +6,8 @@
 
 from typing import List, Tuple
 
+from llama_stack.apis.common.content_types import URL
+
 from llama_stack.apis.models.models import ModelType
 from llama_stack.distribution.datatypes import (
     ModelInput,
@@ -154,6 +156,11 @@ def get_distribution_template() -> DistributionTemplate:
             toolgroup_id="builtin::code_interpreter",
             provider_id="code-interpreter",
         ),
+        ToolGroupInput(
+            toolgroup_id="mcp::filesystem",
+            provider_id="model-context-protocol",
+            mcp_endpoint=URL(uri="http://localhost:8002/sse"),
+        ),
     ]
     embedding_model = ModelInput(
         model_id="all-MiniLM-L6-v2",
```
3. run distro_codegen.py
4. llama stack build --template dev --run

before this pr, the `llama stack run` would fail w/ `AttributeError:
'dict' object has no attribute 'uri'`, after it will succeed.

llama_stack/distribution/stack.py

@@ -96,7 +96,10 @@ async def register_resources(run_config: StackRunConfig, impls: Dict[Api, Any]):
 
         method = getattr(impls[api], register_method)
         for obj in objects:
-            await method(**obj.model_dump())
+            # we want to maintain the type information in arguments to method.
+            # instead of method(**obj.model_dump()), which may convert a typed attr to a dict,
+            # we use model_dump() to find all the attrs and then getattr to get the still typed value.
+            await method(**{k: getattr(obj, k) for k in obj.model_dump().keys()})
 
         method = getattr(impls[api], list_method)
         response = await method()