chore: added mxf file support for adding files and drag and drop optoon (#43)

Author: manoj1749

lib/screens/dashboard/components/add_files.dart

@@ -25,6 +25,7 @@ class AddFilesButton extends StatelessWidget {
             'mpg2',
             'vob',
             'mkv',
+            'mxf',
           ],
           mimeTypes: ['video/*'],
         ),

lib/screens/dashboard/dashboard.dart

@@ -48,7 +48,7 @@ class _DashboardState extends State<Dashboard> {
               final List<XFile> fileData = data.files;
               List<XFile> validFiles = [];
               RegExp validExtensions = RegExp(
-                  r'(\.dvr-ms|\.m2v|\.mpg|\.ts|\.wtv|\.mp4|\.mpg2|\.vob|\.mkv)$');
+                  r'(\.dvr-ms|\.m2v|\.mpg|\.ts|\.wtv|\.mp4|\.mpg2|\.vob|\.mkv|\.mxf)$');
               print(validExtensions.hasMatch(fileData[0].path));
               for (XFile file in fileData) {
                 if (validExtensions.hasMatch(file.path)) {