fix: asyncio not saving interrupt state

[pkit]

During prepare_save we must unconditionally trigger an interrupt to ensure the guest gets notified after restore. The guest may have suppressed notifications, but after snapshot/restore it needs to be woken up regardless.

Fixes #5554

Changes

Fixes a bug where guest would hang indefinitely on interrupts after resume.

Reason

See above.

License Acceptance

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PR Checklist

• I have read and understand CONTRIBUTING.md.
• I have run tools/devtool checkbuild --all to verify that the PR passes
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• I have described what is done in these changes, why they are needed, and
  how they are solving the problem in a clear and encompassing way.
• I have updated any relevant documentation (both in code and in the docs)
  in the PR.
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• When making API changes, I have followed the
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• I have tested all new and changed functionalities in unit tests and/or
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---

• This functionality cannot be added in rust-vmm.

[pkit]

I will add some tests soon.

[pkit]

@dobrac I have improved your tests to iterate until pending ops queue is reproduced.
Now it quite reliably repros in under 10 iterations for me locally.

[codecov]

Codecov Report

❌ Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.23%. Comparing base (d130c7d) to head (4671013).
⚠️ Report is 2 commits behind head on main.

⚠️ Current head 4671013 differs from pull request most recent head 97d23a9

Please upload reports for the commit 97d23a9 to get more accurate results.

Files with missing lines	Patch %	Lines
...vmm/src/devices/virtio/block/virtio/io/async_io.rs	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5568      +/-   ##
==========================================
- Coverage   83.24%   83.23%   -0.01%     
==========================================
  Files         277      277              
  Lines       29263    29268       +5     
==========================================
+ Hits        24359    24362       +3     
- Misses       4904     4906       +2     

Flag	Coverage Δ
5.10-m5n.metal	83.57% <77.77%> (-0.01%)	⬇️
5.10-m6a.metal	82.91% <77.77%> (-0.01%)	⬇️
5.10-m6g.metal	80.19% <77.77%> (-0.01%)	⬇️
5.10-m6i.metal	83.57% <77.77%> (-0.01%)	⬇️
5.10-m7a.metal-48xl	82.90% <77.77%> (-0.01%)	⬇️
5.10-m7g.metal	80.18% <77.77%> (-0.01%)	⬇️
5.10-m7i.metal-24xl	83.54% <77.77%> (-0.01%)	⬇️
5.10-m7i.metal-48xl	83.54% <77.77%> (-0.01%)	⬇️
5.10-m8g.metal-24xl	80.17% <77.77%> (-0.02%)	⬇️
5.10-m8g.metal-48xl	80.18% <77.77%> (-0.01%)	⬇️
6.1-m5n.metal	83.60% <77.77%> (-0.01%)	⬇️
6.1-m6a.metal	82.94% <77.77%> (-0.02%)	⬇️
6.1-m6g.metal	80.18% <77.77%> (-0.01%)	⬇️
6.1-m6i.metal	83.60% <77.77%> (-0.01%)	⬇️
6.1-m7a.metal-48xl	82.93% <77.77%> (-0.01%)	⬇️
6.1-m7g.metal	80.18% <77.77%> (-0.02%)	⬇️
6.1-m7i.metal-24xl	83.62% <77.77%> (-0.01%)	⬇️
6.1-m7i.metal-48xl	83.61% <77.77%> (-0.02%)	⬇️
6.1-m8g.metal-24xl	80.18% <77.77%> (-0.01%)	⬇️
6.1-m8g.metal-48xl	80.18% <77.77%> (-0.01%)	⬇️

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[pkit]

Codecov idea of "coverage" seems incorrect here. Flagging a debug print is not the best use of coverage checks. So, ignored.

[pkit]

@bchalios @kalyazin I'm not sure how to kick-off the codecov pass again, other than that this one should be ready.