feat: Add concept for DeviceCaps & BlockCaps

[Xuanwo]

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

Part of #1200

This PR will be the base for #1200, which adds caps for different devices and verifies them.

Checklist

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

Related issues or PRs (optional)

#1200

---

This PR was primarily authored with Codex using GPT-5-Codex-MAX and then hand-reviewed by me. I AM responsible for every change made in this PR. I aimed to keep it aligned with our goals, though I may have missed minor issues. Please flag anything that feels off, I'll fix it quickly.

[codecov]

Codecov Report

❌ Patch coverage is 58.82353% with 14 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
foyer-storage/src/io/device/partial.rs	0.00%	6 Missing ⚠️
foyer-storage/src/io/device/noop.rs	0.00%	4 Missing ⚠️
foyer-storage/src/io/device/file.rs	25.00%	3 Missing ⚠️
foyer-storage/src/io/device/combined.rs	90.90%	1 Missing ⚠️

Files with missing lines	Coverage Δ
foyer-storage/src/engine/block/engine.rs	87.26% <100.00%> (+0.04%)	⬆️
foyer-storage/src/io/device/fs.rs	92.45% <100.00%> (+0.29%)	⬆️
foyer-storage/src/io/device/mod.rs	100.00% <100.00%> (ø)
foyer-storage/src/io/device/combined.rs	74.48% <90.90%> (+2.07%)	⬆️
foyer-storage/src/io/device/file.rs	66.03% <25.00%> (-1.61%)	⬇️
foyer-storage/src/io/device/noop.rs	11.11% <0.00%> (-0.76%)	⬇️
foyer-storage/src/io/device/partial.rs	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

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[MrCroxx]

Hi, Xuanwo. Thank you for contribution.

I'm a bit confused about the relationship between BlockCaps and #1200. Maybe I didn't explain it clearly enough in #1200. The main purpose of #1200 is to add a method for the device/io engine (and if we consider introducing opendal, it might actually be needed at the io engine layer) to return the compatibility of the device. Then, the engine uses a compatibility check to determine whether the device/io engine can be used under this engine.

Could you please explain the relationship between this PR and #1200 if I misunderstand it?