Add option to disable blurhash previews (#11188)

* Add option to disable blurhash previews

* Update option text

* Change options order

app/javascript/mastodon/initial_state.js

@@ -20,5 +20,6 @@ export const mascot = getMeta('mascot');
 export const profile_directory = getMeta('profile_directory');
 export const isStaff = getMeta('is_staff');
 export const forceSingleColumn = !getMeta('advanced_layout');
+export const useBlurhash = getMeta('use_blurhash');
 
 export default initialState;