feat(ui): add image viewer overlay

- Works on txt2img, canvas and workflows tabs, img2img has its own side-by-side view
- In workflow editor, the is closeable only if you are in edit mode, else it's always there
- Press `i` to open
- Press `esc` to close
- Selecting an image or changing image selection opens the viewer
- When generating, if auto-switch to new image is enabled, the viewer opens when an image comes in

To support this change, I organized and restructured some tab stuff.

invokeai/frontend/web/public/locales/en.json

@@ -361,7 +361,8 @@
         "bulkDownloadRequestFailed": "Problem Preparing Download",
         "bulkDownloadFailed": "Download Failed",
         "problemDeletingImages": "Problem Deleting Images",
-        "problemDeletingImagesDesc": "One or more images could not be deleted"
+        "problemDeletingImagesDesc": "One or more images could not be deleted",
+        "backToEditor": "Back to {{tab}} (Esc)"
     },
     "hotkeys": {
         "searchHotkeys": "Search Hotkeys",
@@ -584,6 +585,14 @@
         "upscale": {
             "desc": "Upscale the current image",
             "title": "Upscale"
+        },
+        "backToEditor": {
+            "desc": "Closes the Image Viewer and shows the Editor View (Text to Image tab only)",
+            "title": "Back to Editor"
+        },
+        "openImageViewer": {
+            "desc": "Opens the Image Viewer (Text to Image tab only)",
+            "title": "Open Image Viewer"
         }
     },
     "metadata": {