Add MaxAlternatingSum algorithm implementation

[Jashnavi25]

This PR adds a Java implementation of Max Alternating Sum to the devutils package.

Includes: ✔ Javadoc documentation ✔ Clean formatting and package declaration ✔ Sorting + arithmetic based optimal algorithm ✔ Follows TheAlgorithms conventions

Time Complexity: O(n log n) Space Complexity: O(n)