wip: walkthrough pie

[visiky]

• label 切换 inner、outer 时，offset 的响应式适配
• 中心文本的fontSize 响应式适配
  • 单测
• 文档走查

利用 css 的 fontSize 可以设置百分比，来使用自适应文本大小的效果：

依赖:
G2: antvis/G2#2981
G2: antvis/G2#2987

[github-actions]

🎊 PR Preview 86f45b4 has been successfully built and deployed to https://antvis-G2Plot-preview-pr-1877.surge.sh

🕐 Build time: 580.152s

_{🤖 By surge-preview}

[lgtm-com]

This pull request fixes 1 alert when merging d0d6268 into 5454d86 - view on LGTM.com

fixed alerts:

• 1 for Overwritten property

[lgtm-com]

This pull request fixes 1 alert when merging 158a269 into 5454d86 - view on LGTM.com

fixed alerts:

• 1 for Overwritten property

[lgtm-com]

This pull request introduces 3 alerts and fixes 1 when merging 1f69f59 into 5454d86 - view on LGTM.com

new alerts:

• 2 for Useless assignment to local variable
• 1 for Unused variable, import, function or class

fixed alerts:

• 1 for Overwritten property

[lgtm-com]

This pull request introduces 2 alerts and fixes 1 when merging d409059 into 5454d86 - view on LGTM.com

new alerts:

• 2 for Useless assignment to local variable

fixed alerts:

• 1 for Overwritten property

[lgtm-com]

This pull request introduces 2 alerts and fixes 1 when merging 86f45b4 into d88a3fa - view on LGTM.com

new alerts:

• 2 for Useless assignment to local variable

fixed alerts:

• 1 for Overwritten property