0dd9bdefa gui: Refactor to use WalletController (João Barbosa)
8fa271f08 gui: Add WalletController (João Barbosa)
cefb399e2 gui: Use AutoConnection for WalletModel::unload signal (João Barbosa)
Pull request description:
This PR is a subset of the work done in the context of #13100. This change consists in extracting from the application class the code that manages the wallet models. The role of the `WalletController` instance is to coordinate wallet operations and the window.
Backport of Core PR15101
Depends on D4619