feat: KV cache based on predis

[susnux]

• requires 3rdparty first feat: add predis as a dependency for Valkey cluster support 3rdparty#2496

Summary

Implemented a new memcache implementation based on predis which does not require any PHP modules to be installed but instead relies on the pure PHP library predis.

This adds support for recent releases of Redis and Valkey (e.g. v8 or v9).
Some features are still missing (numbered databases in clusters) but this will be added soon by predis.

AI was used for documentation texts of config example and test generation.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI