Adds Kotlin solution for problems 846 and 978

[technophilist]

• File(s) Modified: 0846-hand-of-straights.kt , 0978-longest-turbulent-subarray.kt
• Language(s) Used: Kotlin
• Submission URL: https://leetcode.com/problems/hand-of-straights/submissions/937218387/ , https://leetcode.com/problems/longest-turbulent-subarray/submissions/936670040/

[a93a]

Thanks @t3chkid Looks good !