fix(dropdown): define dropdown interaction

[LEEHONCN]

affects: @gio-design/components

@gio-design/components@20.11.1

• 下拉框
  • 定义交互逻辑，当未传visible参数点击overlay区域会关闭下拉框。

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@gio-design/components@20.11.1

• Dropdown
  • define dropdown interaction, it will be close after click the overlay area without visible.

[azure-pipelines]

Deploy preview for ready! ✅ https://deploy-preview-450--gio-design.surge.sh

[codecov]

Codecov Report

Merging #450 (c1fc343) into master (9e6373b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #450   +/-   ##
=======================================
  Coverage   77.32%   77.32%           
=======================================
  Files         111      111           
  Lines        3630     3630           
  Branches      863      864    +1     
=======================================
  Hits         2807     2807           
  Misses        818      818           
  Partials        5        5           

Impacted Files	Coverage Δ
...es/components/src/components/dropdown/Dropdown.tsx	100.00% <100.00%> (ø)

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[azure-pipelines]

Deploy preview for ready! ✅ https://deploy-preview-450--gio-design.surge.sh