Additon of "Hard" Labeled Sorting Problems in sorting.md

[Debaditya-Som]

Problem Statement :

The number of "Hard" labeled assignment questions now included in the sorting.md file under the Assignments section is inadequate to challenge the learner sufficiently. This limitation makes it a bit difficult to comprehend sorting algorithms and related ideas on a deeper level.

Proposed solution : To the sorting.md file, add a full set of correctly labeled "Hard" level sorting challenges. These challenges should include a variety of sorting algorithms, edge situations, and advanced ideas.

[Debaditya-Som]

@kunal-kushwaha If this issue gets approved, I would love to work on it.