refactor: Drop CrcReader

[roypat]

While it's a nice, rusty abstraction, it's really overkill here, given that we're using "100 lines to do the work of 5" (as Riccardo aptly put it).

Changes

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Reason

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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
  build checks on all supported architectures.
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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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---

• This functionality cannot be added in rust-vmm.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.40%. Comparing base (32a77ca) to head (c635783).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5398      +/-   ##
==========================================
+ Coverage   82.37%   82.40%   +0.03%     
==========================================
  Files         266      266              
  Lines       30580    30566      -14     
==========================================
  Hits        25189    25189              
+ Misses       5391     5377      -14     

Flag	Coverage Δ
5.10-c5n.metal	82.38% <100.00%> (-0.02%)	⬇️
5.10-m5n.metal	82.38% <100.00%> (-0.01%)	⬇️
5.10-m6a.metal	81.66% <100.00%> (-0.01%)	⬇️
5.10-m6g.metal	78.98% <100.00%> (-0.02%)	⬇️
5.10-m6i.metal	82.38% <100.00%> (-0.01%)	⬇️
5.10-m7a.metal-48xl	81.65% <100.00%> (?)
5.10-m7g.metal	78.98% <100.00%> (-0.02%)	⬇️
5.10-m7i.metal-24xl	82.35% <100.00%> (?)
5.10-m7i.metal-48xl	82.35% <100.00%> (?)
5.10-m8g.metal-24xl	78.98% <100.00%> (?)
5.10-m8g.metal-48xl	78.98% <100.00%> (?)
6.1-c5n.metal	82.42% <100.00%> (-0.01%)	⬇️
6.1-m5n.metal	82.42% <100.00%> (-0.01%)	⬇️
6.1-m6a.metal	81.70% <100.00%> (-0.01%)	⬇️
6.1-m6g.metal	78.98% <100.00%> (-0.02%)	⬇️
6.1-m6i.metal	82.42% <100.00%> (-0.01%)	⬇️
6.1-m7a.metal-48xl	81.69% <100.00%> (?)
6.1-m7g.metal	78.98% <100.00%> (-0.02%)	⬇️
6.1-m7i.metal-24xl	82.43% <100.00%> (?)
6.1-m7i.metal-48xl	82.43% <100.00%> (?)
6.1-m8g.metal-24xl	78.98% <100.00%> (?)
6.1-m8g.metal-48xl	78.98% <100.00%> (?)

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