feat(comp:button): style update and group support gap

[danranVm]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

What is the new behavior?

• 重构样式，根据视觉规范进行调整， 同时支持 css variable
• button group 支持 gap 配置

Other information

[idux-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #1235 (9b5b189) into main (d93b815) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1235   +/-   ##
=======================================
  Coverage   93.01%   93.01%           
=======================================
  Files         317      317           
  Lines       29136    29140    +4     
  Branches     3307     3309    +2     
=======================================
+ Hits        27101    27105    +4     
  Misses       2035     2035           

Impacted Files	Coverage Δ
packages/components/button/src/Button.tsx	98.83% <100.00%> (+0.01%)	⬆️
packages/components/button/src/ButtonGroup.tsx	100.00% <100.00%> (ø)
packages/components/button/src/types.ts	100.00% <100.00%> (ø)
packages/components/tag/src/Tag.tsx	100.00% <100.00%> (ø)
packages/components/textarea/src/Textarea.tsx	100.00% <100.00%> (ø)
packages/components/tree/src/Tree.tsx	95.06% <100.00%> (+0.02%)	⬆️

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