Add the reference to the FreeIPA pages in the Navigation bar

[carma12]

The current solution of the WebUI includes two main sections only: 'Identity' and 'Policy'. Ideally, all the sections and subpages references should be replicated (using as reference the current FreeIPA WebUI structure) and added to be shown in the main Navigation bar.

The routings should be handled by the react-router-dom library.