Add EmptyState component

ts/components/conversation/media-gallery/EmptyState.tsx

@@ -0,0 +1,29 @@
+/**
+ * @prettier
+ */
+import React from 'react';
+
+import * as Colors from '../../styles/Colors';
+
+interface Props {
+  label: string;
+}
+
+const styles = {
+  container: {
+    display: 'flex',
+    justifyContent: 'center',
+    alignItems: 'center',
+    flexGrow: 1,
+
+    fontSize: 28,
+    color: Colors.TEXT_SECONDARY,
+  } as React.CSSProperties,
+};
+
+export class EmptyState extends React.Component<Props, {}> {
+  public render() {
+    const { label } = this.props;
+    return <div style={styles.container}>{label}</div>;
+  }
+}