<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **Refactor**
- Simplified the user interface by always displaying the new All Pages view, removing the feature flag and old page version.
- Updated selection interactions to use shift+click on document items instead of checkboxes.
- Centralized drag-and-drop functionality in document list items and simplified drag handle behavior.
- Generalized new page button component to accept standard HTML attributes.
- Changed test ID attributes on new page buttons and list headers to use standard `data-testid`.
- **Bug Fixes**
- Added stable test identifiers to new page buttons, document list items, menu items, and operation buttons for improved test reliability.
- Enabled external drag-and-drop support on the trash button.
- **Tests**
- Streamlined and updated end-to-end tests to match the new selection flow and UI changes, removing outdated or redundant test cases.
- Simplified utility functions and wait conditions in test helpers for better accuracy and maintainability.
- Updated selectors in tests to reflect new document item identifiers and centralized page element retrieval using utility functions.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
fix AF-2068, AF-2069, AF-1175, AF-2061, AF-2079, AF-2034, AF-2080, AF-1960, AF-2081
1. replace `dnd-kit` with `@atlaskit/pragmatic-drag-and-drop`
2. allow creating split views by drag & drop the following
a. WorkbenchLinks (route links), like journals, trash, all docs
b. doc refs
c. tags/collection
3. style adjustments to split view
4. remove split view's feature flag and make it GA for electron
https://github.com/user-attachments/assets/6a3e4a25-faa2-4215-8eb0-983f44db6e8c
