WebGPURenderer: Improve PointsNodeMaterial

[sunag]

Related issue: #30254, #29659 (comment)

Description

This PR introduces improvements to PointsNodeMaterial which is now extended from SpriteNodeMaterial therefore brings additional resources. It is also the successor of InstancedPointsNodeMaterial, and resolves issues related to logarithmic depth.

I also separated the circle into a shape, so that users can use different types of shapes in PointsNodeMaterial.

The main motivation is to avoid "duplicate code" and facilitate maintenance.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	339.51 79.09	339.51 79.09	+0 B +0 B
WebGPU	491 136.35	490.73 136.38	-273 B +33 B
WebGPU Nodes	490.46 136.24	490.19 136.27	-273 B +35 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	465.35 112.14	465.35 112.14	+0 B +0 B
WebGPU	560.3 151.75	561.25 152.06	+949 B +314 B
WebGPU Nodes	516.39 141.54	516.63 141.65	+240 B +111 B