chore(vm,stats): fix warnings about paradox struct visibilities

[fogti]

These are present in public VM API, and rust/cargo constantly complain about them (non-public item used in public item, essentially).

[n0toose]

I noticed this after a toolchain update earlier today but ignored it for starters, thanks!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.58%. Comparing base (21daf60) to head (5e31ee1).
⚠️ Report is 14 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1265      +/-   ##
==========================================
- Coverage   77.90%   77.58%   -0.32%     
==========================================
  Files          26       26              
  Lines        3824     3824              
==========================================
- Hits         2979     2967      -12     
- Misses        845      857      +12     

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[jounathaen]

So I'm not sure if this is a good fix. To me it reads like clippy doesn't understand the sealed-trait pattern, or we are using the sealed trait pattern incorrectly. An #[allow(private_interfaces)] might be the more appropriate solution here.
Anyway, this only occurs on nightly, so I'd suggest postponing this until we hit the issue on stable Rust.

[fogti]

Doesn't appear to be present in beta rustc, post-poned for now.