Migrate from classnames to clsx

[TrySound]

• esm support
• smaller without umd wrapper
• probably faster

[codecov-io]

Codecov Report

Merging #1306 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1306   +/-   ##
=======================================
  Coverage   90.39%   90.39%           
=======================================
  Files          59       59           
  Lines        1738     1738           
=======================================
  Hits         1571     1571           
  Misses        167      167

Impacted Files	Coverage Δ
source/Collection/CollectionView.js	90.19% <ø> (ø)	⬆️
source/Grid/Grid.js	94.44% <ø> (ø)	⬆️
source/Masonry/Masonry.js	95.45% <ø> (ø)	⬆️
source/List/List.js	75% <100%> (ø)	⬆️
source/Table/Table.js	89.09% <100%> (ø)	⬆️
source/Table/SortIndicator.js	100% <100%> (ø)	⬆️

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[wuweiweiwu]

Nice!