Refactor Wallet component code re: app initialization

[dmosites]

[GiuntaLucas]

To be clear, do we have to initializate the list of the wallet to the initialization of the app instead of the re initializate the list when we click to the button "connect wallet" ?

[gpxl-dev]

I am making some fairly significant changes to this file as a part of #417, so I've assigned myself here. If anyone wants to contribute in the meantime it might be easiest to propose some improvements for discussion rather than actually implement.