Data Connections: Create a new top-level page (#50018)

* Feature Flags: introduce a flag for enabling the Data Connections page

* Feature Flags: generate schemas

* Navigation: add navigation weight for the Data Connections page

* NavLink: add a comment pointing out where icon names can be looked up

* NavTree: add a new page called Data Connections

* fix(Api): prefix the navigation IDs with the parent ("data-connections")

* feat(Frontend): add a basic page with four tabs

* feat(Plugins): add a hook for importing an app plugin

* feat(Plugins): add a component for loading app plugins anywhere

* feat(Data Connections): load the cloud-onboarding app under the "Cloud onboarding" tab

* feat(Data Connections): generate a proper nav model to highlight active tabs

* test(Data Connections): add tests

* refactor(Data Connections): update temporary text content

This is only used as a placeholder until the tabs are under development.

* refactor(Data Cnnnections): move /pages to /tabs

* refactor(Data Connections): remove the `types.ts` file as it is not referenced by any module

* feat(Data Connections): only register routes if feature is enabled

public/app/routes/routes.tsx

@@ -8,6 +8,7 @@ import { contextSrv } from 'app/core/services/context_srv';
 import UserAdminPage from 'app/features/admin/UserAdminPage';
 import LdapPage from 'app/features/admin/ldap/LdapPage';
 import { getAlertingRoutes } from 'app/features/alerting/routes';
+import { getRoutes as getDataConnectionsRoutes } from 'app/features/data-connections/routes';
 import { getLiveRoutes } from 'app/features/live/pages/routes';
 import { getRoutes as getPluginCatalogRoutes } from 'app/features/plugins/admin/routes';
 import { getProfileRoutes } from 'app/features/profile/routes';
@@ -431,6 +432,7 @@ export function getAppRoutes(): RouteDescriptor[] {
     ...getProfileRoutes(),
     ...extraRoutes,
     ...getPublicDashboardRoutes(),
+    ...getDataConnectionsRoutes(),
     {
       path: '/*',
       component: ErrorPage,