feat(admin, admin-ui, medusa-js, medusa-react, medusa): Support Admin Extensions (#4761)

Co-authored-by: Rares Stefan <948623+StephixOne@users.noreply.github.com>
Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/admin-ui/ui/src/utils/extensions.ts

@@ -0,0 +1,30 @@
+import {
+  Extension,
+  Route,
+  RouteExtension,
+  RouteSegment,
+  SettingExtension,
+  WidgetExtension,
+} from "../types/extensions"
+
+export function isWidgetExtension(
+  extension: Extension
+): extension is WidgetExtension {
+  return "config" in extension && extension.config.type === "widget"
+}
+
+export function isRouteExtension(
+  extension: Extension
+): extension is RouteExtension {
+  return "config" in extension && extension.config.type === "route"
+}
+
+export function isSettingExtension(
+  extension: Extension
+): extension is SettingExtension {
+  return "config" in extension && extension.config.type === "setting"
+}
+
+export function isRoute(route: Route | RouteSegment): route is Route {
+  return "Page" in route
+}