Add docs page for `AnthropicFoundryChatGenerator` component

[bilgeyucel]

Code link: https://github.com/deepset-ai/haystack-core-integrations/blob/main/integrations/anthropic/src/haystack_integrations/components/generators/anthropic/chat/foundry_chat_generator.py

[Aarkin7]

Opened #11812 with a new guide page for AnthropicFoundryChatGenerator covering Azure Foundry auth, streaming, tools, and pipeline usage.