refactor: switch to typescript

[kt3k]

This PR change the language to TypeScript.

[codecov-commenter]

Codecov Report

Merging #2796 into master will decrease coverage by 11.78%.
The diff coverage is 93.75%.

@@             Coverage Diff             @@
##           master    #2796       +/-   ##
===========================================
- Coverage   82.00%   70.21%   -11.79%     
===========================================
  Files          60       63        +3     
  Lines        5162     6548     +1386     
  Branches        0     1496     +1496     
===========================================
+ Hits         4233     4598      +365     
- Misses        929     1454      +525     
- Partials        0      496      +496     

Impacted Files	Coverage Δ
src/api.axis.ts	79.62% <ø> (ø)
src/api.category.ts	18.75% <ø> (ø)
src/api.color.ts	50.00% <ø> (ø)
src/api.data.ts	87.87% <ø> (ø)
src/api.donut.ts	100.00% <ø> (ø)
src/api.flow.ts	2.89% <ø> (ø)
src/api.focus.ts	83.78% <ø> (ø)
src/api.grid.ts	75.86% <ø> (ø)
src/api.group.ts	30.00% <ø> (ø)
src/api.legend.ts	100.00% <ø> (ø)
... and 116 more

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