Fix shortcut editor not considering transient values

[jdpurcell]

This PR fixed 2 issues with the shortcut editor dialog.

1. Assuming all shortcuts are set to / saved with their default values, edit the "Show File Info" shortcut, changing it from "i" to "t". Click OK only on the "Modify Shortcuts" dialog, but do not click OK/Apply on the "Settings" dialog. Now try to edit the "Show in Finder/Explorer" shortcut, setting it to "i". You'll get an error saying "i" is already bound to "Show File Info", because the validation is only looking at the saved settings.
2. Edit any shortcut, change the key binding to something else. Click OK only on the "Modify Shortcuts" dialog, but do not click OK/Apply on the "Settings" dialog. Now try to edit the same shortcut again. When the editor dialog appears, it still has the original/saved value, rather than the new changed value.