Fix attached entities staying too bright

[TheCrazy17]

Summary

CObject::PreRender only recalculates an entity's contact-surface brightness ("lighting") while it isn't attached to anything, so an attached entity keeps whatever value it had at attach time (the constructor default, which renders much too bright) forever.

CClientEntity::DoAttaching now copies the lighting value from whatever the entity is attached to, every frame, mirroring what vanilla hand-held objects already do with their owning ped.

Any entity attached to another (e.g. via attachElements) renders visibly too bright/washed-out compared to its surroundings, because it's stuck with its default lighting value instead of picking up the lighting of whatever it's attached to.

Motivation

Fixes #2203.

Test plan

• Attached an object to a vehicle/ped in a dark area and confirmed it now matches the lighting of the entity it's attached to, instead of rendering at the default (too bright) value.
• Moved the attached entity between differently-lit areas and confirmed the brightness keeps updating every frame instead of getting stuck at the value from attach time.

Checklist

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