Improve pagination

[afc163]

• 调整默认分页选项的个数，使其宽度更统一。Need property for fixed length of pagination element ant-design/ant-design#18201
• 新增 totalBoundaryShowSizeChanger 属性。
• 页数选择器的默认选项从 10,25,50,100 修改为 10,20,50,100。

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[codecov]

Codecov Report

Merging #260 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master    #260   +/-   ##
======================================
  Coverage    90.7%   90.7%           
======================================
  Files           3       3           
  Lines         312     312           
  Branches      108     108           
======================================
  Hits          283     283           
  Misses         29      29

Impacted Files	Coverage Δ
src/Options.jsx	92.3% <ø> (ø)	⬆️
src/Pagination.jsx	90.43% <100%> (ø)	⬆️

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