Add tooltips on server status indicators for federated sharing / tidy up Federated/Federation settings section(s)

Description • I just learnt that you DON'T need green status in federation for the servers to actually federate. • Green status is just to symbolize successful exchange of contact lists which means you can just add the usernames yourself in the search bar without the suggestions and it would work. • This is an important and relieving discovery for me, because I typically waste a lot of time when trying to get green status with two servers to test federated stuff. ![Sample image]( Steps to reproduce See notes on federating : Expected behavior • I think hovering over the status icons should explain what is possible or what the dots mean right in the UI • I addition to existing overview text, users can be directed to hover over the status icon to learn more about the current status. cc: @nextcloud/d Nextcloud Server version master Operating system None PHP engine version None Web server None Databa…