feat: added dynamic class-name feature via classNames attribute

[vijaypushkin]

Summary

The proposed feature is to add a new syntax for dynamically adding classes to React components. This syntax would be similar to the ngClass directive in Angular, allowing developers to use a classNames attribute to add or remove classes based on certain conditions.

View RFC

How did you test this change?

1. I ran yarn build react/index,react-dom/index --type=UMD
2. Made changes in fixtures/packaging/babel-standalone/dev.html as follows:

    <script type="text/babel">
      const isHovering = false;
      const isDisabled = true;
      ReactDOM.render(
        <button classNames={[
          "primary",
          ["teal", "semi-transparent", isHovering && ["hover", "darken-2"]],
          {loading: true, 'is-disabled': isDisabled},
          undefined,
          false,
          null,
          `custom-class`
        ]}>Click Me!</button>,
        document.getElementById('container')
      );
    </script>

and output was generated as expected

<div id="container">
  <button class="primary teal semi-transparent loading is-disabled custom-class">Click Me!</button>
</div>

Related Issues
#3138, #16705, #20050

[react-sizebot]

Comparing: 559e83a...de18653

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	+0.28%	164.18 kB	164.65 kB	+0.32%	51.78 kB	51.94 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.27%	171.57 kB	172.04 kB	+0.32%	53.99 kB	54.16 kB
facebook-www/ReactDOM-prod.classic.js	+0.19%	570.19 kB	571.26 kB	+0.24%	100.62 kB	100.86 kB
facebook-www/ReactDOM-prod.modern.js	+0.19%	553.93 kB	555.00 kB	+0.24%	97.80 kB	98.04 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable-semver/react-dom/umd/react-dom.production.min.js	+0.29%	164.02 kB	164.49 kB	+0.32%	52.08 kB	52.25 kB
oss-stable/react-dom/umd/react-dom.production.min.js	+0.29%	164.09 kB	164.56 kB	+0.33%	52.10 kB	52.27 kB
oss-stable-semver/react-dom/cjs/react-dom.production.min.js	+0.28%	164.11 kB	164.57 kB	+0.31%	51.76 kB	51.91 kB
oss-stable/react-dom/cjs/react-dom.production.min.js	+0.28%	164.18 kB	164.65 kB	+0.32%	51.78 kB	51.94 kB
oss-experimental/react-dom/umd/react-dom.production.min.js	+0.28%	171.41 kB	171.88 kB	+0.22%	54.27 kB	54.39 kB
oss-stable-semver/react-dom/umd/react-dom.profiling.min.js	+0.27%	173.00 kB	173.47 kB	+0.30%	54.47 kB	54.64 kB
oss-stable/react-dom/umd/react-dom.profiling.min.js	+0.27%	173.07 kB	173.55 kB	+0.30%	54.50 kB	54.66 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	+0.27%	171.57 kB	172.04 kB	+0.32%	53.99 kB	54.16 kB
oss-stable-semver/react-dom/cjs/react-dom.profiling.min.js	+0.27%	173.74 kB	174.21 kB	+0.31%	54.19 kB	54.36 kB
oss-stable/react-dom/cjs/react-dom.profiling.min.js	+0.27%	173.81 kB	174.28 kB	+0.31%	54.21 kB	54.38 kB
oss-experimental/react-dom/cjs/react-dom-unstable_testing.production.min.js	+0.26%	177.78 kB	178.25 kB	+0.26%	56.32 kB	56.47 kB
oss-experimental/react-dom/umd/react-dom.profiling.min.js	+0.26%	180.40 kB	180.87 kB	+0.23%	56.60 kB	56.73 kB
oss-experimental/react-dom/cjs/react-dom.profiling.min.js	+0.26%	181.21 kB	181.68 kB	+0.30%	56.40 kB	56.57 kB

Generated by 🚫 dangerJS against de18653

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