Remove LeetCode problems from Queue implementation

- Remove rotten_oranges_bfs.r file (LeetCode Rotten Oranges problem)
- Update DIRECTORY.md to reflect pure Queue data structure only
- Keep only queue_operations.r with comprehensive Queue and PriorityQueue implementations
- Focus on educational data structure implementation without problem-solving examples

Author: Brijesh03032001

DIRECTORY.md

@@ -43,7 +43,6 @@
   * [Binary Search Tree](https://github.com/TheAlgorithms/R/blob/HEAD/data_structures/binary_search_tree.r)
   * Queue
     * [Queue Operations](https://github.com/TheAlgorithms/R/blob/HEAD/data_structures/Queue/queue_operations.r)
-    * [Rotten Oranges BFS](https://github.com/TheAlgorithms/R/blob/HEAD/data_structures/Queue/rotten_oranges_bfs.r)
 
 ## Dynamic Programming
   * 0