feat(react): add useFeatureFlag to experimental entrypoint

Author: joshblack

packages/react/src/__tests__/__snapshots__/exports.test.ts.snap

@@ -324,6 +324,7 @@ exports[`@primer/react/experimental should not update exports without a semver c
   "type UnderlinePanelsPanelProps",
   "type UnderlinePanelsProps",
   "type UnderlinePanelsTabProps",
+  "useFeatureFlag",
   "useOverflow",
   "useSlots",
 ]

packages/react/src/experimental/index.ts

@@ -68,7 +68,7 @@ export {UnderlinePanels} from './UnderlinePanels'
 export type {UnderlinePanelsProps, UnderlinePanelsTabProps, UnderlinePanelsPanelProps} from './UnderlinePanels'
 
 export {SkeletonBox, SkeletonText, SkeletonAvatar} from './Skeleton'
-export {FeatureFlags, DefaultFeatureFlags} from '../FeatureFlags'
+export {FeatureFlags, DefaultFeatureFlags, useFeatureFlag} from '../FeatureFlags'
 export type {FeatureFlagsProps} from '../FeatureFlags'
 
 export {FilteredActionList} from '../FilteredActionList'