feat(driver,iour): detect multishot support

[Berrysoft]

Close #831

I hope the code is robust enough...

[Copilot]

Pull request overview

This PR adds runtime detection for io-uring “multishot” support (e.g., RecvMulti, AcceptMulti) so the driver can decide whether to submit a multishot SQE or fall back to a non-multishot operation, addressing #831 (“no public API to probe if io-uring supports RecvMulti”).

Changes:

• Introduces sys/iour/multishot.rs with probing logic and a detect() helper to classify SQEs as multishot-supported/unsupported.
• Updates the io-uring driver submission path to use is_entry_supported() (multishot-aware) instead of opcode-only probing.
• Refactors BufControl to expose new_inner/release_inner APIs that operate on an io_uring::Submitter (enabling probing code to register a buf ring without a full Driver).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
compio-driver/src/sys/iour/multishot.rs	Adds runtime probing + SQE inspection to infer multishot support.
compio-driver/src/sys/iour/mod.rs	Routes SQE support checks through multishot-aware detection before falling back.
compio-driver/src/sys/iour/buffer_pool.rs	Allows buf-ring register/unregister using a Submitter directly (for probes).

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[George-Miao]

This is some non-trivial task to do. I really think this detection should be an optional feature instead of default behavior... And if user choose not to detect, just let it fail.

One other possibility I can think of is instead of detecting it in driver, move the logic to net: keep a global AtomicBool "not_supported" for each op, and when user calls corresponding op, if not_supported is true, use fallback op, otherwise perform the op and check results, if it's an Unsupported error, flip the flag and fallback; otherwise return.

[Berrysoft]

Too complex to move the code to compio-net. Let's just add docs about it.