GrafanaUI: feature toggle access in Grafana UI (#104500)

* add set/get feature toggles functions to grafana/ui

* configure grafana/ui feature toggle localeFormatPreference in app init

* revert more complex approach and use contained access to global

packages/grafana-ui/src/utils/featureToggle.ts

@@ -0,0 +1,13 @@
+import { FeatureToggles } from '@grafana/data';
+
+type FeatureToggleName = keyof FeatureToggles;
+
+/**
+ * Check a featureToggle
+ * @param featureName featureToggle name
+ * @param def default value if featureToggles aren't defined, false if not provided
+ * @returns featureToggle value or def.
+ */
+export function getFeatureToggle(featureName: FeatureToggleName, def = false) {
+  return window.grafanaBootData?.settings.featureToggles[featureName] ?? def;
+}