API: actualBeamMode fix

[bakajikara]

Resolves: #30449

actualBeamMode will now return the interpreted value for all ChordRests instead of BeamMode::AUTO.

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[bakajikara]

The failed unit tests reflect differences in how beam is applied in corrupted files, but I don't believe this will cause significant issues.
Now that actualBeamMode returns BeamMode::MID instead of BeamMode::AUTO, the beam will connect even in situations where a1->endTick() < cr->tick() (I believe this only happens with corrupted files, but is that correct?).