perf: optimize color modes

[gregberge]

ColorModeProvider converts all colors into variables, it is not useful, only specified colors in modes are needed.

[codecov]

Codecov Report

Merging #185 (7771b8a) into main (074f36f) will increase coverage by 0.11%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
+ Coverage   90.92%   91.04%   +0.11%     
==========================================
  Files          56       56              
  Lines        1003     1016      +13     
  Branches      186      187       +1     
==========================================
+ Hits          912      925      +13     
  Misses         90       90              
  Partials        1        1              

Impacted Files	Coverage Δ
packages/core/src/colorModes.tsx	90.78% <100.00%> (+0.57%)	⬆️
packages/core/src/customProperties.ts	100.00% <100.00%> (ø)
packages/styled-components/src/colorModes.ts	100.00% <100.00%> (ø)

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