feat: add ttl and time_field support to CacheChecker

[Mariam-Amin12]

• fixes Add TTL / expiration support to CacheChecker #12967

Proposed Changes:

Added optional TTL support to CacheChecker to allow cached documents to expire.

• Added an optional ttl parameter.
• Added a configurable time_field parameter for the cache timestamp.
• A cache entry is considered a hit only when its timestamp is within the configured TTL.
• Missing, malformed, or invalid timestamps are treated as cache misses when TTL is enabled.
• Preserved the existing behavior when ttl=None.
• Added support for both synchronous and asynchronous cache checking.

How did you test it?

Added and ran unit tests covering:

• Fresh cache entries within the TTL
• Expired cache entries
• Missing timestamp fields
• ISO timestamp strings
• Naive datetime timestamps (no tzinfo)
• Malformed timestamp strings
• Non-datetime timestamp values
• Numeric TTL values (seconds, not just timedelta)
• Serialization/deserialization round-tripping with ttl and time_field set
• Behavior when TTL is not configured (backward compatibility)
• Async CacheChecker behavior with TTL (fresh + expired)

Ran:

hatch run test:unit test/components/caching/

Result: 26 passed

Notes for the reviewer

The existing behavior is preserved when ttl=None. TTL validation is only applied when TTL is configured.

Checklist

• I have read the [contributors guidelines](https://github.com/deepset-ai/haystack/blob/main/CONTRIBUTING.md) and the [code of conduct](https://github.com/deepset-ai/haystack/blob/main/code_of_conduct.txt).
• I have updated the related issue with new insights and changes.
• I have added unit tests and updated the docstrings.
• I've used one of the [conventional commit types](https://www.conventionalcommits.org/en/v1.0.0/) for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I have documented my code.
• I have added a release note file, following the [contributors guidelines](https://github.com/deepset-ai/haystack/blob/main/CONTRIBUTING.md#release-notes).
• I have run [pre-commit hooks](https://github.com/deepset-ai/haystack/blob/main/CONTRIBUTING.md#setting-up-your-development-environment) and fixed any issue.

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[github-actions]

Hi @Mariam-Amin12, thanks for your interest in contributing to Haystack! 🙏

⚠️ Issue #12967 is already being addressed by open pull request(s) #12979. Before opening a PR for an issue, please check whether a PR is already linked to it, and consider contributing to the existing PR instead. We may close duplicate PRs to keep the review queue manageable.

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