Add Big-O time and space complexity comments for sorting algorithms

[codeahl]

This PR adds time and space complexity documentation to several sorting algorithm implementations in the repository. The following changes were made:

BubbleSort – Added best, average, and worst-case time complexity (O(n²)) and space complexity (O(1)) comments.
MergeSort – Added time complexity (O(n log n)) and space complexity (O(n)) comments.
QuickSort – Added best, average (O(n log n)), and worst-case (O(n²)) time complexity and space complexity (O(log n) recursive stack) comments.
SelectionSort – Added time complexity (O(n²)) and space complexity (O(1)) comments.
InsertionSort – Added time complexity (best: O(n), worst: O(n²)) and space complexity (O(1)) comments.
HeapSort – Added time complexity (O(n log n)) and space complexity (O(1)) comments.
TopologicalSort – Added comments describing the DFS approach, linear ordering of DAGs, and complexity (time: Θ(V + E), space: O(V + E)).

More comments will be needed however, to make time/space complexity clearer for the other algorithms.

Fixes #7123

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.61%. Comparing base (e7c3e1f) to head (6dee3dc).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #7155   +/-   ##
=========================================
  Coverage     78.61%   78.61%           
  Complexity     6824     6824           
=========================================
  Files           766      766           
  Lines         22607    22607           
  Branches       4444     4444           
=========================================
  Hits          17773    17773           
  Misses         4119     4119           
  Partials        715      715           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[DenizAltunkapan]

Thank you for your contribution @codeahl