[feature] Allow web wallets to also optionally provide windowFeatures in the wallet cloud explorer

[huckym]

What problem does this new feature solve?

Currently the wallet window is opened like a normal window which leads to user jumping around tabs. Instead if the wallet just opened as a separate small window overlay (just like the extension wallets), the user can stay focused on the dapp while being able to take wallet actions in the wallet window

Describe the solution you'd like

Instead if the wallet was able to specify windowFeatures it could customize the size/position etc.. of the wallet window

cc: @pedrouid