[memory refactor][6/n] Update naming and routes (#839)

Making a few small naming changes as per feedback:

- RAGToolRuntime methods are called `insert` and `query` to keep them
more general
- The tool names are changed to non-namespaced forms
`insert_into_memory` and `query_from_memory`
- The REST endpoints are more REST-ful

llama_stack/providers/tests/tools/test_tools.py

@@ -96,14 +96,14 @@ class TestTools:
         )
 
         # Insert documents into memory
-        await tools_impl.rag_tool.insert_documents(
+        await tools_impl.rag_tool.insert(
             documents=sample_documents,
             vector_db_id="test_bank",
             chunk_size_in_tokens=512,
         )
 
         # Execute the memory tool
-        response = await tools_impl.rag_tool.query_context(
+        response = await tools_impl.rag_tool.query(
             content="What are the main topics covered in the documentation?",
             vector_db_ids=["test_bank"],
         )