Enable to comment out an entire block by simply placing the cursor on the first line of the block

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> `blockCommentCommand` comments out the selected area, but it's a pain to select the entire area before you comment out. So we need to have a feature that you can comment out an entire block by simply placing the cursor on the first line of the block. This issue is linked to the pull request (#135533 )