Added Java program to find Kth maximum and minimum element in an array

[isameeralikhan]

Description

Added a Java Program to find Kth Max and Min element in an array using min and max-heaps implemented using priority queues.

Related Issue

This PR closes # Adds a new feature.

Motivation and Context

Adds new feature.

Screenshots (if any)

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.