feat: Add OpenAI Conversations API (#3429)

# What does this PR do?

Initial implementation for `Conversations` and `ConversationItems` using
`AuthorizedSqlStore` with endpoints to:
- CREATE
- UPDATE
- GET/RETRIEVE/LIST
- DELETE

Set `level=LLAMA_STACK_API_V1`.

NOTE: This does not currently incorporate changes for Responses, that'll
be done in a subsequent PR.

Closes https://github.com/llamastack/llama-stack/issues/3235

## Test Plan
- Unit tests
- Integration tests

Also comparison of [OpenAPI spec for OpenAI
API](https://github.com/openai/openai-openapi/tree/manual_spec)
```bash
oasdiff breaking --fail-on ERR docs/static/llama-stack-spec.yaml https://raw.githubusercontent.com/openai/openai-openapi/refs/heads/manual_spec/openapi.yaml --strip-prefix-base "/v1/openai/v1" \
--match-path '(^/v1/openai/v1/conversations.*|^/conversations.*)'
```

Note I still have some uncertainty about this, I borrowed this info from
@cdoern on https://github.com/llamastack/llama-stack/pull/3514 but need
to spend more time to confirm it's working, at the moment it suggests it
does.

UPDATE on `oasdiff`, I investigated the OpenAI spec further and it looks
like currently the spec does not list Conversations, so that analysis is
useless. Noting for future reference.

---------

Signed-off-by: Francisco Javier Arceo <farceo@redhat.com>

uv.lock

@@ -1773,6 +1773,7 @@ dependencies = [
     { name = "python-jose", extra = ["cryptography"] },
     { name = "python-multipart" },
     { name = "rich" },
+    { name = "sqlalchemy", extra = ["asyncio"] },
     { name = "starlette" },
     { name = "termcolor" },
     { name = "tiktoken" },
@@ -1887,7 +1888,7 @@ requires-dist = [
     { name = "jsonschema" },
     { name = "llama-stack-client", specifier = ">=0.2.23" },
     { name = "llama-stack-client", marker = "extra == 'ui'", specifier = ">=0.2.23" },
-    { name = "openai", specifier = ">=1.100.0" },
+    { name = "openai", specifier = ">=1.107" },
     { name = "opentelemetry-exporter-otlp-proto-http", specifier = ">=1.30.0" },
     { name = "opentelemetry-sdk", specifier = ">=1.30.0" },
     { name = "pandas", marker = "extra == 'ui'" },
@@ -1898,6 +1899,7 @@ requires-dist = [
     { name = "python-jose", extras = ["cryptography"] },
     { name = "python-multipart", specifier = ">=0.0.20" },
     { name = "rich" },
+    { name = "sqlalchemy", extras = ["asyncio"], specifier = ">=2.0.41" },
     { name = "starlette" },
     { name = "streamlit", marker = "extra == 'ui'" },
     { name = "streamlit-option-menu", marker = "extra == 'ui'" },