Introduce Coin Selection page

[johnny9]

This PR depends on #445

This is the first iteration of the Coin Selection menu

The option to open the Coin Selection menu is a QSetting that is toggled on/off in the ellipsis menu on the Send page. When enabled, the user can click on the Select inputs button and the Coin Selection menu will be push on the stack from below. The Coin Selection menu will list possible inputs and a checkbox is used to select the coins. Locked coins are not selectable and instead of a check box, they have a locked icon.

https://github.com/user-attachments/assets/f148d231-d9e9-4923-91f3-8e422049bbf5