Implement CustomRadixTransform for wave viewers (#2434)

1. Add CustomRadix{Def,Apply}Annotation to define and apply custom radix.
2. Add CustomRadixConfigFileAnnotation to output a JSON config file so
   users can generate scripts on their own.

Reviewed-by: Jiuyang Liu <liu@jiuyang.me>
Co-authored-by: sinofp <sinofp@tuta.io>