Accessibility improvements in settings (#32968)

* Add more playwright axe tests to settings dialogs

* Fix axe issue heading-order

* Fix heading order

* Iterate

* Update snapshots

* Iterate

* Update snapshots

* Iterate

* Update screenshot

* Iterate

* Iterate

* Update snapshot

apps/web/playwright/e2e/settings/appearance-user-settings-tab/theme-choice-panel.spec.ts

@@ -23,7 +23,7 @@ test.describe("Appearance user settings tab", () => {
         test(
             "should be rendered with the light theme selected",
             { tag: "@screenshot" },
-            async ({ page, app, util }) => {
+            async ({ page, app, util, axe }) => {
                 // Assert that 'Match system theme' is not checked
                 await expect(util.getMatchSystemThemeSwitch()).not.toBeChecked();
 
@@ -34,6 +34,8 @@ test.describe("Appearance user settings tab", () => {
                 await expect(util.getHighContrastTheme()).not.toBeChecked();
 
                 await expect(util.getThemePanel()).toMatchScreenshot("theme-panel-light.png");
+
+                await expect(axe).toHaveNoViolations();
             },
         );