Given a string s, return all the palindromic permutations (without duplicates) of it.
You may return the answer in any order. If s has no palindromic permutation, return an empty list.
Example 1:
Input: s = "aabb" Output: ["abba","baab"]
Example 2:
Input: s = "abc" Output: []
Constraints:
1 <= s.length <= 16sconsists of only lowercase English letters.