Display the summary of the wallet policy as a confirmation step in the participation flow

[nondiremanuel]

Follow up of https://github.com/wizardsardine/liana/issues/620#issuecomment-2312502818

Currently a user that participates to a wallet via email token, doesn't have the visibility of the wallet policy he is joining. We should discuss what's the best way (if required at all) to display this information. I was thinking to insert it as a confirmation step when the user inserts the token and imports the wallet. Something like: "Congratulations! You joined WalletName. This is WalletName spending policy: wallet policy"

One possible issue is that as per my understanding the keys here would not have aliases, not even the ones the wallet creator gave, making it more difficult for the participant to the wallet to understand which is his key.