feat(Coupon): support for checkbox usage

[CatsAndMice]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 18 lines in your changes are missing coverage. Please review.

Project coverage is 89.60%. Comparing base (f53e134) to head (36f61dd).
Report is 17 commits behind head on main.

Files	Patch %	Lines
packages/vant/src/coupon-list/CouponList.tsx	13.33%	11 Missing and 2 partials ⚠️
packages/vant/src/coupon-cell/CouponCell.tsx	76.19%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12744      +/-   ##
==========================================
- Coverage   89.81%   89.60%   -0.22%     
==========================================
  Files         257      257              
  Lines        6835     6876      +41     
  Branches     1660     1674      +14     
==========================================
+ Hits         6139     6161      +22     
- Misses        369      388      +19     
  Partials      327      327              

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[CatsAndMice]

@chenjiahan 已对code review问题进行修改

[inottn]

单选的交互并不完全适用于多选，可以适当优化下多选对应的 demo

[CatsAndMice]

已优化多选对应的 demo，并且增加 list-button slot 用于开发者自定义底部提交按钮 @chenjiahan @inottn

[CatsAndMice]

@chenjiahan 麻烦合并下这个PR

[chenjiahan]

好的，明天处理下