Login dialog with SignMessage instead of adding an AccessKey

[zavodil]

Is your feature request related to a problem? Please describe. I want to create an application that does not require login with an AccessKey for the contract, but only requires SignMessage. This is a new application that hasn't been used before, so app doesn't know which wallet (account_id and software) the current user has.

Describe the solution you'd like The user clicks a button, and a wallet selection dialog opens. After this, the selected wallet prompts the user to SignMessage.

Additional context This feature can be useful for many initiatives that will use NEAR accounts for authentication. For example, for AI