support rspack plugin and glass-easel-miniprogram-rspack-template

[gaoachao]

Currently glass-easel uses webpack as bundler and provides webpack plugin. why not use rspack as bundler? Although the glass-easel-template-compiler and glass-easel-stylesheet-compiler are already rust-based with good performance, webpack itself still has many performance bottlenecks, such as the make and seal stages, which are single-threaded. I'd like to try it.

• glass-easel-miniprogram-rspack-plugin
• glass-easel-miniprogram-rspack-template

[LastLeaf]

Note that the main problem is to handle miniprogram directory structure properly.