* feat(kotlin): add kotlin code for utils file.
* Update ListNode.kt
* Update PrintUtil.kt
* fix: add the header comment for linkedlist_stack class.
* fix(kotlin): fix the kotlin file name.
* delete blank line in main function
* add comment for class head.
* delete the old file.
* fix the created time
* delete blank line beneath files.
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Co-authored-by: Yudong Jin <krahets@163.com>
curtishd