[Refactor]: Add LLMRegistry for llm services (#9589)

Co-authored-by: openhands <openhands@all-hands.dev>
Co-authored-by: Graham Neubig <neubig@gmail.com>
Co-authored-by: Engel Nyst <enyst@users.noreply.github.com>

openhands/utils/utils.py

@@ -0,0 +1,37 @@
+from copy import deepcopy
+
+from openhands.core.config.openhands_config import OpenHandsConfig
+from openhands.llm.llm_registry import LLMRegistry
+from openhands.server.services.conversation_stats import ConversationStats
+from openhands.storage import get_file_store
+from openhands.storage.data_models.settings import Settings
+
+
+def setup_llm_config(config: OpenHandsConfig, settings: Settings) -> OpenHandsConfig:
+    # Copying this means that when we update variables they are not applied to the shared global configuration!
+    config = deepcopy(config)
+
+    llm_config = config.get_llm_config()
+    llm_config.model = settings.llm_model or ''
+    llm_config.api_key = settings.llm_api_key
+    llm_config.base_url = settings.llm_base_url
+    config.set_llm_config(llm_config)
+    return config
+
+
+def create_registry_and_convo_stats(
+    config: OpenHandsConfig,
+    sid: str,
+    user_id: str | None,
+    user_settings: Settings | None = None,
+) -> tuple[LLMRegistry, ConversationStats, OpenHandsConfig]:
+    user_config = config
+    if user_settings:
+        user_config = setup_llm_config(config, user_settings)
+
+    agent_cls = user_settings.agent if user_settings else None
+    llm_registry = LLMRegistry(user_config, agent_cls)
+    file_store = get_file_store(user_config.file_store, user_config.file_store_path)
+    convo_stats = ConversationStats(file_store, sid, user_id)
+    llm_registry.subscribe(convo_stats.register_llm)
+    return llm_registry, convo_stats, user_config