Fix using arrow keys to move object when move tool is selected causes changed of focus

[EricEzaM]

Fixes #70789

What a goose chase this was. Turns out inside the _gui_input handling, we call _update_cursor(), which in turn pushes a mouse motion event to the viewport. This RESETS the gui.key_event_accepted to false, when the move tool already accepted the event and set it to true!

So the fix here is actually to ensure viewport->set_default_cursor_shape(c); (at the bottom of _update_cursor()) never gets called because the new cursor is same as current.

This might need to be looked into as this was quite a hard bug to find due to that interaction. Simplfied, this was happening:

• _gui_input
• handle move tool
• move calls accept_event()
• viewport sets gui.key_event_accepted to true
• move calls update_cursor()
• update_cursor() dispatches an event to the viewport via viewport->set_default_cursor_shape(c);
• viewport sets gui.key_event_accepted to false
• handling move tool finished
• viewport checks gui.key_event_accepted - it is now false! When it should be true since move tool handled the event

[Sauermann]

I believe that a better way would be to get rid of the set_default_cursor_shape call for every Mouse-Move.
Please see #59081

[EricEzaM]

Yes you are probably right