[1.5.0] Enable preview of future account balances

Currently, the future account balance can only be displayed in the chart widget on the overview page. However, for multiple accounts, the displayed value refers to the total account balance. Therefore, it would be useful to show the future (e.g. the next 12 months) account balance for a specific account somewhere in the form of a list.

One possibility would be a "Show forecast"-button in the filtered transaction view when clicking on an account on the overview screen.

Alternatively, a display within the financial reports feature is also conceivable.