[BETA] Add OpenAI /images/variations + Topaz API support (#7700)

* feat(main.py): initial commit for `/image/variations` endpoint support

* refactor(base_llm/): introduce new base llm base config for image variation endpoints

* refactor(openai/image_variations/transformation.py): implement openai image variation transformation handler

* fix: test

* feat(openai/): working openai `/image/variation` endpoint calls via sdk

* feat(topaz/): topaz sync image variation call support

Addresses https://github.com/BerriAI/litellm/issues/7593

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* fix(topaz/transformation.py): fix linting errors

* fix(openai/image_variations/handler.py): fix passing json data

* fix(main.py): image_variation/

support async image variation route - `aimage_variation`

* fix(test_get_model_info.py): fix test

* fix: cleanup unused imports

* feat(openai/): add async `/image/variations` endpoint support

* feat(topaz/): support async `/image/variations` calls

* fix: test

* fix(utils.py): fix get_model_info_helper for no model info w/ provider config

handles situation where model info is not known but provider config exists

* test(test_router_fallbacks.py): mark flaky test

* fix: fix unused imports

* test: bump otel load test perf threshold - accounts for current load tests hitting same server

litellm/llms/base_llm/base_utils.py

@@ -16,3 +16,13 @@ class BaseLLMModelInfo(ABC):
     @abstractmethod
     def get_models(self) -> List[str]:
         pass
+
+    @staticmethod
+    @abstractmethod
+    def get_api_key(api_key: Optional[str] = None) -> Optional[str]:
+        pass
+
+    @staticmethod
+    @abstractmethod
+    def get_api_base(api_base: Optional[str] = None) -> Optional[str]:
+        pass