feat: [FC-0044] Course unit - Copy/paste functionality (#884)

Implement copy/paste.

Co-authored-by: monteri <36768631+monteri@users.noreply.github.com>
Co-authored-by: ihor-romaniuk <ihor.romaniuk@raccoongang.com>

src/constants.js

@@ -56,3 +56,14 @@ export const COURSE_BLOCK_NAMES = ({
   vertical: { id: 'vertical', name: 'Unit' },
   component: { id: 'component', name: 'Component' },
 });
+
+export const STUDIO_CLIPBOARD_CHANNEL = 'studio_clipboard_channel';
+
+export const CLIPBOARD_STATUS = {
+  loading: 'loading',
+  ready: 'ready',
+  expired: 'expired',
+  error: 'error',
+};
+
+export const STRUCTURAL_XBLOCK_TYPES = ['vertical', 'sequential', 'chapter', 'course'];