Add C++ solution for 0658-find-k-closest-elements

[AnandVishesh1301]

• File(s) Modified: cpp/0658-find-k-closest-elements.cpp

• Language(s) Used: C++

• Submission URL: https://leetcode.com/problems/find-k-closest-elements/submissions/1668782599

• The file name is lowercase and follows the repository's naming conventions.

• Verified no duplicate file exists in the repository for this problem and language.

• The solution passes all LeetCode test cases.

[AnandVishesh1301]

@neetcode-gh @Ykhan799
Just created this PR to add the above cpp solution! Who can review the same so we can get it merged!
Thanks.