UI: Theme changes (#22880)

* Theme: Updates the theme to align panel & page background colors

* Updated dashboard settings view to be similar to new panel edit

* Updated themes

* Added shadow

* Updates generated files

* Minor fix to inspect drawer

* Clean up old dashboard setttings stuff

* Polish to search

* Updated truth image

* Minor tweaks to dropdown menu

* Updates and alignments between inspect drawer and explore rich history

* removed unused variables

* Minor tweak to light page header bg

public/app/routes/routes.ts

@@ -197,6 +197,7 @@ export function setupAngularRoutes($routeProvider: route.IRouteProvider, $locati
     .when('/explore', {
       template: '<react-container />',
       reloadOnSearch: false,
+      pageClass: 'page-explore',
       resolve: {
         roles: () => (config.viewersCanEdit ? [] : ['Editor', 'Admin']),
         component: () => SafeDynamicImport(import(/* webpackChunkName: "explore" */ 'app/features/explore/Wrapper')),