Closes https://github.com/zed-industries/zed/issues/33221

Bedrock has similar to anthropic caching api, if we want to cache
messages up to a certain point, we should add a special block into that
message.

Additionally, we can cache tools definition by adding cache point block
after tools spec.

See: [Bedrock User Guide: Prompt
Caching](https://docs.aws.amazon.com/bedrock/latest/userguide/prompt-caching.html#prompt-caching-models)

Release Notes:

- bedrock: Added prompt caching support

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Co-authored-by: Oleksiy Syvokon <oleksiy@zed.dev>