Fix incorrect error when log unknown, and add a bunch of tests

[AlCutter]

This PR fixes a couple of bugs in the sqlite storage implementation where:

• it incorrectly returns an error when config for an unknown log is requested.
• it failed to check rows.Err after iterating

[codecov-commenter]

Codecov Report

❌ Patch coverage is 55.55556% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 25.99%. Comparing base (61e4168) to head (a9fc148).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
persistence/sqlite/sql.go	55.55%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #592      +/-   ##
==========================================
+ Coverage   24.91%   25.99%   +1.08%     
==========================================
  Files          29       29              
  Lines        2408     2454      +46     
==========================================
+ Hits          600      638      +38     
- Misses       1680     1683       +3     
- Partials      128      133       +5     

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[phbnf]

nit: a docstring, or a named variable would help to understand what this bool does.

[AlCutter]

Good call - the interface this actually implements is over in omniwitness, which is now a bit disjoint and not so discoverable.