feat: Accessibility Activation (#29958)

apps/meteor/app/theme/client/imports/general/reset.css

apps/meteor/client/providers/UserProvider/UserProvider.tsx

apps/meteor/client/sidebar/header/hooks/useAccountItems.tsx

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

...t/views/account/accessibility/HighContrastUpsellModal.tsx

apps/meteor/client/views/account/accessibility/fontSizes.ts

...ws/account/accessibility/hooks/useAdsjustableFontSize.tsx

.../account/accessibility/hooks/useCreateFontStyleElement.ts

apps/meteor/client/views/account/accessibility/themeItems.ts

apps/meteor/client/views/account/routes.tsx

apps/meteor/client/views/account/sidebarItems.tsx

...ent/views/account/themes/HighContrastUpsellModal.spec.tsx

apps/meteor/client/views/account/themes/ProviderMock.tsx

apps/meteor/client/views/account/themes/ThemePage.spec.tsx

apps/meteor/packages/rocketchat-i18n/i18n/en.i18n.json

apps/meteor/server/methods/saveUserPreferences.ts

...rest-typings/src/v1/users/UsersSetPreferenceParamsPOST.ts