Examples: Added damping to LDrawLoader example

[WestLangley]

This example already had an animation loop, so I added damping.

[WestLangley]

Unrelated to this PR, this example appears to have a bug when toggling "Merge Model".

master: https://threejs.org/examples/webgl_loader_ldraw.html

/ping @gkjohnson

[gkjohnson]

Unrelated to this PR, this example appears to have a bug when toggling "Merge Model".

Looks like this broke between r146 and r147

[gkjohnson]

Specifically it broke in #24868.

cc @yomboprime @sbgib

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And a live link for this PR:
https://raw.githack.com/WestLangley/three.js/dev-ldraw_example/examples/webgl_loader_ldraw.html

[WestLangley]

The visibility calculation fails here when toggling "Merge Model". Some inputs can be undefined.

three.js/examples/webgl_loader_ldraw.html

Lines 157 to 158 in f2a90fd

	// Hide objects with building step > gui setting
	c.visible = c.userData.buildingStep <= guiData.buildingStep;