Overall this PR does the following:
- add top level menu Window
- add Minimize and Zoom actions to Window menu
- move Sending/Receiving address to Window
- remove Help->Debug menu and add one menu entry for each debug window tab in the Window menu
The ellipsis in the name of `Sending/Receiving addresses` actions are be removed, according to common practices (https://stackoverflow.com/a/637708).
Ellipsis at the end of the name of menu actions suggest that user input is expected.
Backport of Core PR14573 and PR16514
PR16514 removes the `RPCConsole::tabFocus` method introduced in the first PR, but never used.