Add blurhash (#10630)

* Add blurhash

* Use fallback color for spoiler when blurhash missing

* Federate the blurhash and accept it as long as it's at most 5x5

* Display unknown media attachments as blurhash placeholders

* Improve style of embed actions and spoiler button

* Change blurhash resolution from 3x3 to 4x4

* Improve dependency definitions

* Fix code style issues

app/javascript/mastodon/features/report/components/status_check_box.js

@@ -35,6 +35,7 @@ export default class StatusCheckBox extends React.PureComponent {
             {Component => (
               <Component
                 preview={video.get('preview_url')}
+                blurhash={video.get('blurhash')}
                 src={video.get('url')}
                 alt={video.get('description')}
                 width={239}