Create avl_tree_implementation

[pstreemaze]

Java AVL tree implementation

Description

AVL tree implemenation

Fixes #(issue number) Wrote whole code - All rotations covered

Please delete options that are not relevant

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] This change requires a documentation update

Checklist:

• [1 ] I have read the contribution guidelines before making this PR.
• [1 ] My code follows the style guidelines of this project
• [1 ] I have performed a self-review of my own code
• [1 ] I have commented in my code, particularly in hard-to-understand areas
• [ 1] I have made corresponding changes to the documentation (Language folder or any other readme instructed to)
• [1 ] My changes generates no new warnings
• [1 ] I have added tests that prove my fix is effective or that my feature works