Make sure react demo is up to date and uses modern react code

[sequba]

Page URL

https://hyperformula.handsontable.com/guide/integration-with-react.html

Improvement description

• update react framework to the latest version in the demo
• make the code clean, logical, modern, complient with the current best react practices
• use only the function components

[sequba]

Also test the demo with React 19 RC