fix(comp:card): add css class to footer button

[sallerli1]

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?

card的footer样式是特殊处理的，并且是直接引用的button的样式，导致自己写的button样式被影响

What is the new behavior?

给footer中的button加上class，不影响用户自定义的button

Other information

[idux-bot]

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[codecov]

Codecov Report

Merging #1660 (22701ce) into main (192ca82) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 22701ce differs from pull request most recent head d60d112. Consider uploading reports for the commit d60d112 to get more accurate results

@@           Coverage Diff           @@
##             main    #1660   +/-   ##
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  Coverage   92.59%   92.59%           
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  Files         345      345           
  Lines       32285    32285           
  Branches     3685     3685           
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  Hits        29895    29895           
  Misses       2390     2390           

Files Changed	Coverage Δ
packages/components/card/src/Card.tsx	99.36% <100.00%> (ø)