0.0.2-preview

• Legacy shaders are integrated into two shaders.
• The number of textures is reduced experimental
• Added Clipping Matte feature for HDRP.
• Removed almost all the warrnings when compiling shaders.
• Grafted graphics tests from Scriptable Render Pipelines.
• Reorganized documents.
• Reorganized repository folder structure.
• Added feature model list FeatureModel_en.md