feat: RFC: tools API rework

# What does this PR do?
This PR proposes updates to the tools API in Inference and Agent.

Goals:
1. Agent's tool specification should be consistent with Inference's tool spec, but with add-ons.
2. Formal types should be defined for built in tools. Currently Agent tools args are untyped, e.g. how does one know that `builtin::rag_tool` takes a `vector_db_ids` param or even how to know 'builtin::rag_tool' is even available (in code, outside of docs)?

Inference:
1. BuiltinTool is to be removed and replaced by a formal `type` parameter.
2. 'brave_search' is replaced by 'web_search' to be more generic. It will still be translated back to brave_search when the prompt is constructed to be consistent with model training.
3. I'm not sure what `photogen` is. Maybe it can be removed?

Agent:
1. Uses the same format as in Inference for builtin tools.
2. New tools types are added, i.e. knowledge_sesarch (currently rag_tool), and MCP tool.
3. Toolgroup as a concept will be removed since it's really only used for MCP.
4. Instead MCPTool is its own type and available tools provided by the server will be expanded by default. Users can specify a subset of tool names if desired.

Example snippet:
```

agent = Agent(
    client,
    model=model_id,
    instructions="You are a helpful assistant. Use the tools you have access to for providing relevant answers.",
    tools=[
        KnowledgeSearchTool(vector_store_id="1234"),
        KnowledgeSearchTool(vector_store_id="5678", name="paper_search", description="Search research papers"),
        KnowledgeSearchTool(vector_store_id="1357", name="wiki_search", description="Search wiki pages"),
        # no need to register toolgroup, just pass in the server uri
        # all available tools will be used
        MCPTool(server_uri="http://localhost:8000/sse"),
        # can specify a subset of available tools
        MCPTool(server_uri="http://localhost:8000/sse", tool_names=["list_directory"]),
        MCPTool(server_uri="http://localhost:8000/sse", tool_names=["list_directory"]),
        # custom tool
        my_custom_tool,
    ]
)
```

## Test Plan
# What does this PR do?


## Test Plan
# What does this PR do?


## Test Plan

llama_stack/apis/inference/inference.py

@@ -17,18 +17,18 @@ from typing import (
     runtime_checkable,
 )
 
-from pydantic import BaseModel, Field, field_validator
+from pydantic import BaseModel, Field
 from typing_extensions import Annotated
 
 from llama_stack.apis.common.content_types import ContentDelta, InterleavedContent, InterleavedContentItem
 from llama_stack.apis.models import Model
 from llama_stack.apis.telemetry.telemetry import MetricResponseMixin
 from llama_stack.models.llama.datatypes import (
-    BuiltinTool,
     SamplingParams,
     StopReason,
     ToolCall,
     ToolDefinition,
+    ToolDefinitionDeprecated,
     ToolPromptFormat,
 )
 from llama_stack.providers.utils.telemetry.trace_protocol import trace_protocol
@@ -156,23 +156,14 @@ Message = Annotated[
 register_schema(Message, name="Message")
 
 
+# TODO: move this to agent.py where this is used
 @json_schema_type
 class ToolResponse(BaseModel):
     call_id: str
-    tool_name: Union[BuiltinTool, str]
+    tool_name: str
     content: InterleavedContent
     metadata: Optional[Dict[str, Any]] = None
 
-    @field_validator("tool_name", mode="before")
-    @classmethod
-    def validate_field(cls, v):
-        if isinstance(v, str):
-            try:
-                return BuiltinTool(v)
-            except ValueError:
-                return v
-        return v
-
 
 class ToolChoice(Enum):
     """Whether tool use is required or automatic. This is a hint to the model which may not be followed. It depends on the Instruction Following capabilities of the model.
@@ -462,7 +453,8 @@ class Inference(Protocol):
         model_id: str,
         messages: List[Message],
         sampling_params: Optional[SamplingParams] = None,
-        tools: Optional[List[ToolDefinition]] = None,
+        # TODO: remove ToolDefinitionDeprecated in v0.1.10
+        tools: Optional[List[ToolDefinition] | List[ToolDefinitionDeprecated]] = None,
         tool_choice: Optional[ToolChoice] = ToolChoice.auto,
         tool_prompt_format: Optional[ToolPromptFormat] = None,
         response_format: Optional[ResponseFormat] = None,