lifelong learning enhancements tracking issue

[llhuii]

This issue is to track these known lifelong learning added in #72 enhancements to be done:

• KB server need its standalone code directory instead of placing into lib directory
• KB API need to be reviewed again(such as /file/download, /file/upload)
• Reduce KB image size(v0.3.0 is 1.28G showed by docker-images)
• In multi-task-learning of lib code, need to add docs and code comment
• Remove scikit-learn requirement for federated-learning surface-defect-detection example
• Reduce lifelong example image size(v0.3.0 is 1.36G)
• Review the requirements of lib

[JoeyHwong-gk]

(sedna-example-lifelong-learning-atcii-classifier)[https://github.com/kubeedge/sedna/tree/main/examples/lifelong_learning/atcii] run fail

1. backend_type should change to sklearn not tensorflow

[llhuii]

progress:

1. Reduce KB image size(v0.3.0 is 1.28G showed by docker-images) ==> reduced to 315MB

[JoeyHwong-gk]

• S3 storage support is not user-friendly.
• too many param in lifelong-learning/multi-task-learning