Refactor media preview functionality and update localization strings

Moved the mediaPreviewUrl function to the media API for better organization and clarity. Updated the MediaPanel component to include a preview feature for media assets, allowing users to view processed clips. Enhanced the UI to include a dialog for media previews and added corresponding localization strings in both English and Russian for the new preview functionality.

frontend/src/shared/lib/locales/en.ts

@@ -297,6 +297,7 @@ export const en = {
     media: {
       title: 'Media',
       upload: 'Upload',
+      preview: 'Preview',
       manualButton: 'From manual folder',
       importButton: 'Import',
       importTitle: 'Media import',