docs: enable theme switcher for TreeGrid example (#4918)

Co-authored-by: Serhii Kulykov <iamkulykov@gmail.com>

Author: vursen

articles/components/tree-grid/index.adoc

@@ -15,7 +15,7 @@ page-links:
 Tree Grid is a component for displaying hierarchical tabular data grouped into expandable nodes.
 // end::description[]
 
-[.example]
+[.example,themes="lumo,aura"]
 --
 
 ifdef::lit[]

frontend/demo/component/tree-grid/tree-grid-basic.ts

@@ -5,8 +5,8 @@ import { html, LitElement } from 'lit';
 import { customElement } from 'lit/decorators.js';
 import type { GridDataProviderCallback, GridDataProviderParams } from '@vaadin/grid';
 import { getPeople } from 'Frontend/demo/domain/DataService';
-import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 import { applyTheme } from 'Frontend/demo/theme';
+import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 
 @customElement('tree-grid-basic')
 export class Example extends LitElement {

frontend/demo/component/tree-grid/tree-grid-column.ts

@@ -7,8 +7,8 @@ import { html, LitElement } from 'lit';
 import { customElement, state } from 'lit/decorators.js';
 import type { GridDataProviderCallback, GridDataProviderParams } from '@vaadin/grid';
 import { getPeople } from 'Frontend/demo/domain/DataService';
-import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 import { applyTheme } from 'Frontend/demo/theme';
+import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 
 @customElement('tree-grid-column')
 export class Example extends LitElement {

frontend/demo/component/tree-grid/tree-grid-rich-content.ts

@@ -14,8 +14,8 @@ import type { GridColumnBodyLitRenderer } from '@vaadin/grid/lit.js';
 import { columnBodyRenderer } from '@vaadin/grid/lit.js';
 import type { GridTreeToggleExpandedChangedEvent } from '@vaadin/grid/vaadin-grid-tree-toggle.js';
 import { getPeople } from 'Frontend/demo/domain/DataService';
-import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 import { applyTheme } from 'Frontend/demo/theme';
+import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 
 @customElement('tree-grid-rich-content')
 export class Example extends LitElement {

frontend/demo/component/tree-grid/tree-grid-scroll-to-index.ts

@@ -15,8 +15,8 @@ import type {
 } from '@vaadin/grid';
 import type { IntegerFieldChangeEvent } from '@vaadin/integer-field';
 import { getPeople } from 'Frontend/demo/domain/DataService';
-import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 import { applyTheme } from 'Frontend/demo/theme';
+import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
 
 @customElement('tree-grid-scroll-to-index')
 export class Example extends LitElement {