UI refresh for uploaded files

Fixes https://github.com/vector-im/element-web/issues/16557
Fixes https://github.com/vector-im/element-web/issues/9482 (technically)

There's two changes in this:
1. The actual file body in the timeline now has a placeholder thing.
2. We're intentionally dropping all the "Travis uploaded a file" sender profile states.

src/components/views/messages/MImageBody.js

@@ -452,7 +452,7 @@ export default class MImageBody extends React.Component {
 
     // Overidden by MStickerBody
     getFileBody() {
-        return <MFileBody {...this.props} decryptedBlob={this.state.decryptedBlob} />;
+        return <MFileBody {...this.props} decryptedBlob={this.state.decryptedBlob} showGenericPlaceholder={false} />;
     }
 
     render() {