Include all shadow variables in theme object

[colebemis]

Problem

We were not including all shadow variables from Primer Primitives in the Primer React theme object.

Background

In Primer Primitives, colors and shadows are stored in one object. In Primer React, we need to store colors and shadows in two separate objects. We split up the Primer Primitives object using this partitionColors function:

function partitionColors(colors) {
  return {
    colors: filterObject(colors, value => isColorValue(value)),
    shadows: filterObject(colors, value => isShadowValue(value))
  }
}

I figured out that we were omitting some shadow variables in the theme object because isShadowValue() was incorrectly return false when passed some valid shadow values.

Solution

This PR updates the isShadowValue() function to correctly handle more shadow values and adds tests to avoid future regressions.

cc @dmarcey @mattcosta7

[changeset-bot]

🦋 Changeset detected

Latest commit: def1444

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/components	Patch

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[dgreif]

Thanks for adding tests!!