Added algorithm for color contrast ratio. (#1794)

* Added algorithm for color contrast ratio.

* Added comment and example usage in main.

* Fixed calling method in main without creating object.

* Formatted with Google Java Formatter

* Add imports for ColorContrastRatio.java

* updating DIRECTORY.md

* Updated to follow repo conventions. Undid formatting of documents.

* Follow repository conventions.

* Formatted with Google Java Formatter

* Added test method with assetions.

* Formatted with Google Java Formatter

* Update Misc/ColorContrastRatio.java

Co-authored-by: Ayaan Khan <ayaankhan98@gmail.com>

* updating DIRECTORY.md

* Correct javadocs and parameter names.

* Formatted with Google Java Formatter

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Ayaan Khan <ayaankhan98@gmail.com>