Draft: fix memory queues to prevent memory leak

This PR has been replaced by !587 (merged).

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What does this PR do? (Please give us a brief description of what this PR does.)

This PR resolves #600 (closed) and #601 (closed) by re-implementing MemoryKVCache<T>. The new implementation supports capacity limits with Least Recently Used (LRU) eviction. All references to this class have been updated to specify a reasonable capacity limit.

Additional changes have been made to prevent memory leaks and improve reliability:

• All "infinite" cache lifetimes have been replaced with a reasonable limit. This includes those that do not use MemoryKVCache<T> directly.
• The RedisKVCache<T> wrapper class is updated with a new option memoryCacheCapacity. This limits the internal memory cache capacity.
• MemoryKVCache<T> no longer uses garbage collection, and instead starts an independent timer for each entry. This avoids a costly cache sweep and increases eviction accuracy (from 30% to ~0% eviction latency).
• MemoryKVCache<T> no longer requires disposal.

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• I agree to follow this project's Contribution Guidelines
• I have made sure to test this pull request

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Alternate version for Misskey: https://github.com/warriordog/misskey/tree/hazelnoot/fix-memory-caches

This PR is an untested draft!

Open questions:

• Should these limits be configurable? Yes, settings would be good.
• Should this be upstreamed? Yes, change will be upstreamed.
• Does this work reliably? (needs testing)
• Is the new eviction method effective? (needs testing)