Replace react-treebeard with a modern library

[palagdan]

This library causes warnings in a console and is not supported for 5 years :

TreeBeard2: Support for defaultProps will be removed from function components in a future major release. Use JavaScript default parameters instead.

Warning: Transition2 uses the legacy childContextTypes API, which is no longer supported and will be removed in the next major release. Use React.createContext() instead.

_Originally posted by @palagdan in https://github.com/kbss-cvut/s-pipes-editor-ui/issues/61#issuecomment-2317935601_

[blcham]

Current state:

• related React component was refactored here

TODO:

• We can replace the component with this library https://www.npmjs.com/package/rc-tree that is base for all popular react tree libraries. Example: https://tree-react-component.vercel.app/demo/
• An alternative is of course Inteligent tree select -- https://github.com/lecbyjak/intelligent-tree-select