Added utility classes for swapping array elements

[cicirello]

Summary

• SimpleSwapper: utility class for swapping elements within an array
• ValidatedSwapper: utility class for swapping elements within an array, which verifies indexes are different before attempting swap

Closing Issues

Closes #256

Types of changes

• I have read the CONTRIBUTING document.
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvements to existing code, such as refactoring or optimizations (non-breaking)
• Breaking change (fix or feature that would cause existing functionality to change)
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[github-actions]

JaCoCo Test Coverage Summary Statistics

• Coverage: 100%
• Branches: 100%