Support prompt caching in Anthropic generators

[julian-risch]

Is your feature request related to a problem? Please describe.
Anthropic, in particular the models Claude 3.5 Sonnet and Claude 3 Haiku support prompt caching or context caching. Support for Claude 3 Opus is coming soon. We should enable users to use that feature through Haystack to reduce costs and latency.
https://docs.anthropic.com/en/docs/build-with-claude/prompt-caching
https://www.anthropic.com/news/prompt-caching

Describe the solution you'd like
We need to implement support for Anthropic's cache_control parameter in messages.

[julian-risch]

related issue #1003

[vblagoje]

To have a full benefit of prompt caching in Haystack pipelines we need to resolve #1011

[vblagoje]

Support for prompt caching added in https://pypi.org/project/anthropic-haystack/ 1.1.0 release. See our example on how to leverage prompt caching in a "chat with a long research paper" use case.