feat: impl eviction-time disk cache insertion

[MrCroxx]

What's changed and what's your intention?

Please explain IN DETAIL what the changes are in this PR and why they are needed. :D

Delay the disk cache insertion from insertion time to eviction time.

Besides, no longer borrow the in-mem cache as the disk cache in-queue entry index. It is okay to have a gap that may have cache miss between in-mem cache eviction and disk cache insertion. Because after #785 , in-mem cache no longer guarantees that an entry is still available when it is not in the indexer but still in memory.

Changes:

• Delay the disk cache insertion from insertion time to eviction time.
• Never double write the disk cache while in-mem cache insertion.
• Introduce Pipe and Piece as the bridge between in-mem cache and disk cache.
• Refactors on some implementations.

Checklist

• I have written the necessary rustdoc comments
• I have added the necessary unit tests and integration tests
• I have passed make all (or make fast instead if the old tests are not modified) in my local environment.

Related issues or PRs (optional)

close #818

[codecov]

Codecov Report

Attention: Patch coverage is 91.40271% with 19 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
foyer-memory/src/raw.rs	57.89%	8 Missing ⚠️
foyer-memory/src/pipe.rs	89.65%	6 Missing ⚠️
foyer-memory/src/cache.rs	88.88%	2 Missing ⚠️
foyer-storage/src/small/batch.rs	83.33%	2 Missing ⚠️
foyer-storage/src/engine.rs	83.33%	1 Missing ⚠️

Files with missing lines	Coverage Δ
foyer-storage/src/large/batch.rs	85.29% <100.00%> (-0.22%)	⬇️
foyer-storage/src/large/flusher.rs	86.31% <100.00%> (ø)
foyer-storage/src/large/generic.rs	90.73% <100.00%> (+0.81%)	⬆️
foyer-storage/src/large/reclaimer.rs	85.36% <100.00%> (-0.12%)	⬇️
foyer-storage/src/large/recover.rs	90.90% <100.00%> (-0.07%)	⬇️
foyer-storage/src/small/flusher.rs	85.29% <100.00%> (-0.71%)	⬇️
foyer-storage/src/small/generic.rs	75.97% <100.00%> (-1.16%)	⬇️
foyer-storage/src/small/set.rs	94.11% <100.00%> (-0.04%)	⬇️
foyer-storage/src/small/set_manager.rs	89.65% <100.00%> (-0.69%)	⬇️
foyer-storage/src/storage/either.rs	40.81% <100.00%> (ø)
... and 10 more

... and 1 file with indirect coverage changes

[MrCroxx]

More details in risingwavelabs/risingwave#20076