Unify the `border-radius` values of the all components.

[kerwin612]

What's changed?

As shown in the screenshot, the system is filled with various rounded corners of different ratios. Now, Unify the rounded corners into two values: the rounded corners of functional components will be unified to 4, and the rounded corners of container components will be unified to 8. From now on, there will be only two kinds of rounded corner values in the system, and there will be no more inconsistencies.

Checklist

• [x] I have read the Contributing Guide
• [x] I have written the necessary doc or comment.
• [x] I have added the necessary unit tests and all cases have passed.

Add or update API

• [ ] I have added the necessary e2e tests and all cases have passed.