[FEATURE REQUEST] Add Duval's algorithm for Lyndon factorization #7638

I would like to contribute Duval's algorithm for Lyndon factorization in the
com.thealgorithms.strings package. I did not find a Lyndon factorization
implementation in the current source tree or DIRECTORY.md.

Proposed API: LyndonFactorization.factorize(String text) returning
List<String> in non-increasing lexicographic order, using Java's UTF-16
code-unit ordering.

Examples:

• banana -> [b, an, an, a]
• ababab -> [ab, ab, ab]
• empty input -> []
• null input -> NullPointerException

The implementation uses O(n) time and O(1) working space excluding the returned
factors. Tests include an independent check of the Lyndon-word and ordering
properties for every short string over a three-character alphabet.

Reference: https://cp-algorithms.com/string/lyndon_factorization.html

The code and tests have been prepared with AI assistance. Before submitting a
PR, could you confirm whether this addition and assistance disclosure are
acceptable, including how to handle the PR template's "all my own work" item?