chore: Replace `IconButton` in favor of `Button` on `PageHeader` (#31171)

...mponents/Contextualbar/ContextualbarScrollableContent.tsx

apps/meteor/client/components/Page/Page.stories.tsx

apps/meteor/client/components/Page/PageHeader.tsx

apps/meteor/client/components/Page/index.ts

apps/meteor/client/components/PageSkeleton.tsx

.../client/views/account/accessibility/AccessibilityPage.tsx

...iews/account/featurePreview/AccountFeaturePreviewPage.tsx

...nt/views/account/integrations/AccountIntegrationsPage.tsx

.../views/account/omnichannel/OmnichannelPreferencesPage.tsx

...ient/views/account/preferences/AccountPreferencesPage.tsx

...eteor/client/views/account/profile/AccountProfilePage.tsx

...eor/client/views/account/security/AccountSecurityPage.tsx

.../meteor/client/views/account/tokens/AccountTokensPage.tsx

...eteor/client/views/admin/customEmoji/CustomEmojiRoute.tsx

...teor/client/views/admin/customSounds/CustomSoundsPage.tsx

...nt/views/admin/customUserStatus/CustomUserStatusRoute.tsx

apps/meteor/client/views/admin/emailInbox/EmailInboxForm.tsx

apps/meteor/client/views/admin/emailInbox/EmailInboxPage.tsx

...ews/admin/federationDashboard/FederationDashboardPage.tsx

apps/meteor/client/views/admin/import/ImportHistoryPage.tsx