Fix SQLite3 Cell data overflow reading for databases with header.reserved_size set

[JSCU-CNI]

This PR fixes Cell.data reading for databases when parsing a cell value larger than the (usable) page size. Currently the overflow page lookup implementation does not calculate the data_size correctly for databases with header.reserved_size set.

[Schamper]

You know the question that's coming: is it possible to have some test data for this edge case?

Also @PimSanders since you've been looking into SQLite for a little while now, what are your thoughts on this?

[JSCU-CNI]

You know the question that's coming: is it possible to have some test data for this edge case?

The PR for #17 will include test data that covers this change.

[JSCU-CNI]

Added a separate test for this case in 3a09e78.

[PimSanders]

I think I understand where this issue comes from and how the fix works. Seems to me like a good fix for the issue.

Only thing I noticed is that self.page.sqlite.usable_page_size is the same as self.sqlite.usable_page_size, which might make the code a tiny bit more readable.

Haven't been able to test it yet, so correct me if I'm wrong.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (f75cabe) to head (7c44bf1).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dissect/database/sqlite3/sqlite3.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #25   +/-   ##
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  Coverage   0.00%   0.00%           
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  Files        146     146           
  Lines       3880    3879    -1     
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+ Misses      3880    3879    -1     

Flag	Coverage Δ
unittests	0.00% <0.00%> (ø)

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[Schamper]

TIL ruff lints Python inside docstrings.

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

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_{Comparing JSCU-CNI:sqlite-fix-cell-data-overflow-reading (7c44bf1) with main (f75cabe)}