refactor: bump MSRV to v1.88.0 and use if-let-chains

[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

AS IS

But hold it for our dependents..

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)

[codecov]

Codecov Report

Attention: Patch coverage is 72.72727% with 9 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
foyer-memory/src/eviction/lru.rs	0.00%	4 Missing ⚠️
foyer-storage/src/large/generic.rs	0.00%	2 Missing ⚠️
foyer-storage/src/large/reclaimer.rs	0.00%	2 Missing ⚠️
foyer-storage/src/large/serde.rs	50.00%	1 Missing ⚠️

Files with missing lines	Coverage Δ
foyer-bench/src/analyze.rs	97.90% <ø> (+97.90%)	⬆️
foyer-bench/src/exporter.rs	0.00% <ø> (ø)
foyer-bench/src/main.rs	68.19% <100.00%> (+68.19%)	⬆️
foyer-common/src/bits.rs	65.51% <ø> (ø)
foyer-common/src/future.rs	100.00% <ø> (ø)
foyer-common/src/rate.rs	98.11% <ø> (ø)
foyer-common/src/rated_ticket.rs	100.00% <ø> (ø)
foyer-common/src/utils/range.rs	0.00% <ø> (ø)
foyer-memory/src/cache.rs	78.79% <ø> (ø)
foyer-memory/src/eviction/fifo.rs	100.00% <ø> (ø)
... and 36 more

... and 6 files with indirect coverage changes

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