fix: align not trigger when source element width changed

[shaodahong]

Ref: react-component/cascader#79 (comment)

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[codecov]

Codecov Report

Merging #35 into master will increase coverage by 0.44%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #35      +/-   ##
==========================================
+ Coverage   92.24%   92.68%   +0.44%     
==========================================
  Files           3        3              
  Lines         116      123       +7     
  Branches       26       27       +1     
==========================================
+ Hits          107      114       +7     
  Misses          9        9

Impacted Files	Coverage Δ
src/Align.tsx	100% <100%> (ø)	⬆️

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[zombieJ]

看看能不能用 rc-resize-observer替换掉，这边其实也不真的关心尺寸。

[shaodahong]

看看能不能用 rc-resize-observer替换掉，这边其实也不真的关心尺寸。

主要是用于 submenu 展开的时候需要触发 adjustX 或者 adjustX 这种，我现在用 monitorResize 改造了下，看看

[zombieJ]

看了下没问题，在 rc-cascader 里试试，如果 ok 我这边直接合了。

[shaodahong]

link 过去可以了，合吧

[zombieJ]

+ rc-align@3.0.0-alpha.7