dApp - add automatic connection feature for connection manager

[weilbith]

Description

With the current minimal version of the connection manager, the user always has to select the desired provider and connect. The only convenience (though a big one) that his options get remembered and he has not to type them in again. Anyway it would be nice if we could improve this more and make it closer the way it was earlier.

This feature has a lot of discussion potential. A very simple version would be that the user still has to select the provider. But if there are saved provider options, it will automatically use them and if it succeeds, the user can just continue. If it fails, the usual dialog gets shown. The question would be then how the user can ever change the chosen provider options at a later point. Options would be to abuse the connection cancel button (bad user flow, not intuitive) or a section in the user settings (re-using the current dialog without a button).
A more advanced solution would be to also remember the last used provider. The additional question here - while all former ones remain - how to make this happen. So is there then a different single button? Or should the home route always auto-connect (like other pages remember your login). How to change the provider later?

Acceptance criteria

Tasks

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