folder structure change and also skeleton page refactoring

[hokagedemehin]

TASK COMPLETED

• Renamed client to frontend,
• Renamed server to backend,
• Renamed test_root_config to single_spa
• Moved the refactored skeleton page to its own folder called skeleton, which had only four folders namely components, assert, styles, pages inside of it
• Correct all of the import errors in all of the components that was moved inside this folder
• changed the path inside the static-engine.js to conform to the above changes so that it will render the build folder of the frontend