feat(ui): revise generation mode logic

- Canvas generation mode is replace with a boolean `sendToCanvas` flag. When off, images generated on the canvas go to the gallery. When on, they get added to the staging area.
- When an image result is received, if its destination is the canvas, staging is automatically started.
- Updated queue list to show the destination column.
- Added `IconSwitch` component to represent binary choices, used for the new `sendToCanvas` flag and image viewer toggle.
- Remove the queue actions menu in `QueueControls`. Move the queue count badge to the cancel button.
- Redo layout of `QueueControls` to prevent duplicate queue count badges.
- Fix issue where gallery and options panels could show thru transparent regions of queue tab.
- Disable panel hotkeys when on mm/queue tabs.

invokeai/frontend/web/src/features/queue/components/InvokeQueueBackButton.tsx

@@ -15,7 +15,7 @@ export const InvokeQueueBackButton = memo(() => {
   const isLoadingDynamicPrompts = useAppSelector(selectDynamicPromptsIsLoading);
 
   return (
-    <Flex pos="relative" flexGrow={1} minW="240px">
+    <Flex pos="relative" w="192px">
       <QueueIterationsNumberInput />
       <QueueButtonTooltip>
         <Button