Fix getElementRadius returning false for buildings

[TheCrazy17]

Summary

getElementRadius's type switch never had a case for buildings; it fell through to the final return false, even though CClientBuilding already exposes GetModel() the same way objects and peds do. Added the missing case, same pattern already used right below it in GetElementDistanceFromCentreOfMassToBaseOfModel.

Motivation

Fixes #5137.

Test plan

Created a building with createBuilding, called getElementRadius on it; now returns the model's bounding radius instead of false. Also re-tested getElementRadius on a ped, vehicle and object to confirm the existing cases are untouched.

Checklist

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