More idiomatic REST API (#765)

# What does this PR do?

This PR changes our API to follow more idiomatic REST API approaches of
having paths being resources and methods indicating the action being
performed.

Changes made to generator:
1) removed the prefix check of "get" as its not required and is actually
needed for other method types too
2) removed _ check on path since variables can have "_"



## Test Plan

LLAMA_STACK_BASE_URL=http://localhost:5000 pytest -v
tests/client-sdk/agents/test_agents.py

llama_stack/apis/safety/safety.py

@@ -12,7 +12,6 @@ from pydantic import BaseModel, Field
 
 from llama_stack.apis.inference import Message
 from llama_stack.apis.shields import Shield
-
 from llama_stack.providers.utils.telemetry.trace_protocol import trace_protocol
 
 
@@ -49,7 +48,7 @@ class ShieldStore(Protocol):
 class Safety(Protocol):
     shield_store: ShieldStore
 
-    @webmethod(route="/safety/run-shield")
+    @webmethod(route="/safety/run-shield", method="POST")
     async def run_shield(
         self,
         shield_id: str,