chore!: delete deprecated chat models

[mdrxy]

The following modules, which have been marked for removal, have been deleted. Consequently, any attempt to import these from langchain-classic (which re-exports from langchain-community) will break.

• ChatAnthropic (change import to langchain_anthropic.ChatAnthropic)
• AzureChatOpenAI (change import to langchain_openai.AzureChatOpenAI)
• BedrockChat (change import to langchain_aws.ChatBedrock)
• ChatCohere (change import to langchain_cohere.ChatCohere)
• ChatDatabricks (change import to databricks_langchain.ChatDatabricks)
• ChatFireworks (change import to langchain_fireworks.ChatFireworks)
• GigaChat (change import to langchain_gigachat.GigaChat)
• ChatHuggingFace (change import to langchain_huggingface.ChatHuggingFace)
• ChatLiteLLM (change import to langchain_litellm.ChatLiteLLM)
• ChatLiteLLMRouter (change import to langchain_litellm.ChatLiteLLMRouter)
• ChatOllama (change import to langchain_ollama.ChatOllama)
• ChatOpenAI* (change import to langchain_openai.ChatOpenAI)
• ChatPerplexity (change import to langchain_perplexity.ChatPerplexity)
• ChatSambaNovaCloud (change import to langchain_sambanova.ChatSambaNovaCloud)
• ChatSambaStudio (change import to langchain_sambanova.ChatSambaStudio)
• SolarChat (change import to langchain_upstage.ChatUpstage)
• ChatVertexAI (change import to langchain_google_vertexai.ChatVertexAI)
  *ChatOpenAI is kept in this package for now, as many other community chat models inherit from it. It has been removed from __all__ and should not be used. It will be removed at a later date once the other packages can be reconciled.

For any classes that previously imported private methods or utilities from the files containing these classes, those functions have been duplicated into the importing files.