feat: Add Multi-Model Provider Support to Agent Component (#4416)

* Add Multi-Model Provider Support to Agent Component

- Integrated model provider constants from `model_input_constants.py` into the Agent component to support multiple LLM providers
- Added dynamic field management for different model providers (OpenAI, Azure, Groq, Anthropic, NVIDIA)
- Implemented a dropdown for model provider selection with automatic input field updates

* sorted list

* Update agent.py

making custom separate from sort

* chore: remove unit test

---------

Co-authored-by: italojohnny <italojohnnydosanjos@gmail.com>

src/backend/tests/unit/base/models/test_model_constants.py

@@ -1,25 +0,0 @@
-from src.backend.base.langflow.base.models.model_constants import ModelConstants
-
-
-def test_provider_names():
-    # Initialize the ModelConstants
-    ModelConstants.initialize()
-
-    # Expected provider names
-    expected_provider_names = [
-        "AIML",
-        "Amazon Bedrock",
-        "Anthropic",
-        "Azure OpenAI",
-        "Ollama",
-        "Vertex AI",
-        "Cohere",
-        "Google Generative AI",
-        "HuggingFace",
-        "OpenAI",
-        "Perplexity",
-        "Qianfan",
-    ]
-
-    # Assert that the provider names match the expected list
-    assert expected_provider_names == ModelConstants.PROVIDER_NAMES