Do some class/property renaming.

[andy840119]

• CustomizedShaderBufferedDrawNode -> CustomizedShaderDrawNode, not really sure still need Buffered or not 🤔
• MultiShaderBufferedDrawNode and MultiShaderBufferedDrawNodeSharedData -> should remove the Buffered also.
• StepShader.Draw -> Not really should change this name as Template because it's still render to the framebuffer, but not showing.
• StepShader -> Guess should be better to rename as GroupShader because those shaders will render as a group.

Other:

• Not really sure should have Draw property in every customized shader?
• Not really sure should have something like NodeShader or TemplateShader for able make this shader as template or not.