Fix obb-collider to work on text-geometry

[vincentfretin]

Description:

Fix obb-collider to work on text-geometry with obb-collider="centerModel: true"

Changes proposed:

• Don't assume mesh comes from glf-model, use generic el.getObject3D('mesh');
• Call if (this.data.centerModel) { this.centerModel(); } before this.updateCollider(); in init, same as in onModelLoaded, text-geometry doesn't have a model-loaded event so it didn't center the mesh

[dmarcos]

thanks