Add Custom Format Option Label story (#5476)

storybook/stories/CustomFormatOptionLabel.stories.tsx

@@ -0,0 +1,44 @@
+import type { ComponentMeta } from '@storybook/react';
+import * as React from 'react';
+import Select from 'react-select';
+import { Field } from '../components';
+
+import { colourOptions } from '../data';
+
+export default {
+  title: 'Select/CustomFormatOptionLabel',
+  component: Select,
+  argTypes: {},
+} as ComponentMeta<typeof Select>;
+
+export function CustomFormatOptionLabel() {
+  return (
+    <Field
+      label="Custom Format Option Label"
+      htmlFor="custom-format-option-label-id"
+    >
+      <Select
+        inputId="custom-format-option-label-id"
+        defaultValue={colourOptions[2]}
+        options={colourOptions}
+        formatOptionLabel={formatOptionLabel}
+      />
+    </Field>
+  );
+}
+
+function formatOptionLabel(option: typeof colourOptions[number]) {
+  return (
+    <div style={{ display: 'flex', alignItems: 'center', gap: '0.25rem' }}>
+      <div
+        style={{
+          backgroundColor: option.color,
+          borderRadius: 9999,
+          height: 8,
+          width: 8,
+        }}
+      />
+      <div>{option.label}</div>
+    </div>
+  );
+}