Refactor Code to use functional Components - VI

Following files in entity page use class based structures, it will be good to convert them to use functional component.

- MarkupStudioEntry.js
- Entity.js
- EntityRelated.js

Start by reading MarkupStudioEntry.js, Entity.js, and EntityRelated.js to identify their current class-based structures and how they are used within the entity page. Convert the listed components to functional components, then verify that the entity page still behaves as before and that none of the three files retain class-based component structures.

Written by the indexing model from the issue text.