[TF2] Properly remove/scale Spy cigarette/Medic glasses with decapitation/head smash/big head transformations

[FlaminSarge]

Description

This addresses a handful of missing handling cases for player model transformations:

• Decapitated and head-smashed ragdolls keep the Spy's cigarette and the Medic's glasses floating above the severed neck/shortened neck model; this patch hides them under these conditions
• The Big Head transformations do not scale the cigarette/glasses, resulting in them disappearing underneath the enlarged model; this patch scales them so that they appear alongside the enlarged (or shrunken) heads in the correct positions
• Removes iClass param from BuildTorsoScaleTransformations as it is entirely unused