Re-enable shelf action feature

[d2dyno1]

Resolved / Related Issues

• Closes Feature: Add 'Shelf' pane to take bulk actions on items from different paths #12490

This PR introduces minor changes, unless additional changes are requested. The file watcher was implemented quite some time ago and already works properly, thanks to #16900 and #16728. This PR focuses solely on re-enabling this feature, but can be iterated upon to accommodate any undocumented missing features (if any? - not that I'm aware of)

• Re-enabled the command for showing the Shelf pane in production
• Add a "Create link" menu option when dropping an item from the shelf to a folder
• Add a delete bulk action
• Add "View in parent folder" menu option
• Fixed Shelf's file watcher reference counter logic
• ?

Steps used to test these changes

Stability is a top priority for Files and all changes are required to go through testing before being merged into the repo. Please include a list of steps that you used to test this PR.

1. Opened Files
2. Confirmed the action shows up appropriately
3. Confirmed the menu and bulk actions work properly
4. Confirmed that deleting two (or more) files from the same folder using the bulk delete action properly removes them from the Shelf