Respect damage thresholds in damage calculation with bypass option

[arbron]

Vehicles currently have a damage threshold option, but the damage calculation system currently ignores it. It would be respected during calculation and the damage application interface should also have a button to bypass it if desired similar to other damage resistance bypasses.

[Fyorl]

There is some precedent in official content for creatures also having damage thresholds (or at least effects granting them damage thresholds). Could we add attributes.hp.dt to CharacterData and NPCData as well? I already have changes on the vehicle sheet branch to add DT to the HitPointsConfig so no additional changes needed there.