fix(pro:search): overlay zIndex should be larger than container

[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?

从非聚焦状态下直接点击搜索项，搜索项浮层的z-index计算会先于输入框，导致搜索项浮层被遮盖

What is the new behavior?

修复以上问题

Other information

[idux-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #1389 (dbb90c4) into main (e71cd46) will decrease coverage by 0.00%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main    #1389      +/-   ##
==========================================
- Coverage   92.87%   92.87%   -0.01%     
==========================================
  Files         324      324              
  Lines       29814    29820       +6     
  Branches     2480     2481       +1     
==========================================
+ Hits        27690    27695       +5     
- Misses       2124     2125       +1     

Impacted Files	Coverage Δ
packages/pro/search/src/ProSearch.tsx	15.49% <0.00%> (-0.08%)	⬇️
packages/pro/search/src/token.ts	100.00% <100.00%> (ø)
packages/components/select/src/Select.tsx	87.34% <0.00%> (+0.21%)	⬆️

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