feat(ui): add multi-select and batch capabilities

This introduces the core functionality for batch operations on images and multiple selection in the gallery/batch manager.

A number of other substantial changes are included:
- `imagesSlice` is consolidated into `gallerySlice`, allowing for simpler selection of filtered images
- `batchSlice` is added to manage the batch
- The wonky context pattern for image deletion has been changed, much simpler now using a `imageDeletionSlice` and redux listeners; this needs to be implemented still for the other image modals
- Minimum gallery size in px implemented as a hook
- Many style fixes & several bug fixes

TODO:
- The UI and UX need to be figured out, especially for controlnet
- Batch processing is not hooked up; generation does not do anything with batch
- Routes to support batch image operations, specifically delete and add/remove to/from boards

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

@@ -52,6 +52,7 @@
         "unifiedCanvas": "Unified Canvas",
         "linear": "Linear",
         "nodes": "Node Editor",
+        "batch": "Batch Manager",
         "postprocessing": "Post Processing",
         "nodesDesc": "A node based system for the generation of images is under development currently. Stay tuned for updates about this amazing feature.",
         "postProcessing": "Post Processing",