Introduce color operations constant for use in single stat

Could be useful elsewhere

ui/src/shared/constants/colorOperations.js

@@ -0,0 +1,24 @@
+const hexToRgb = hex => {
+  const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex)
+  return result
+    ? {
+        r: parseInt(result[1], 16),
+        g: parseInt(result[2], 16),
+        b: parseInt(result[3], 16),
+      }
+    : null
+}
+
+const averageRgbValues = valuesObject => {
+  const {r, g, b} = valuesObject
+  return (r + g + b) / 3
+}
+
+const trueNeutralGrey = 128
+
+export const isBackgroundLight = backgroundColor => {
+  const averageBackground = averageRgbValues(hexToRgb(backgroundColor))
+  const isLight = averageBackground > trueNeutralGrey
+
+  return isLight
+}