Feature: Added discovering phase to the Status Center

[workbysaran]

Resolved / Related Issues

Fixed UX issues during large folder operations where Status Center appears doing nothing. Users now see real-time discovery progress showing the actual number of items being discovered during the enumeration phase.

Closes: #14057

Steps used to test these changes

1. Open the Files app and navigate to a directory containing a large number of files (100k+)
2. Initiate a copy, move, or delete operation on the large folder
3. Observe the Status Center popup during the operation:

• Initially shows "Discovered X items..." with real-time count updates during enumeration
• Transitions to "Copying/Moving/Deleting X items..." after enumeration completes

4. Verify the UI remains responsive during large folder operations without freezing
5. Test with different operation types (Copy, Move, Delete) to ensure consistent behavior
6. Confirm that it shows the appropriate status text and completed operations display proper completion messages

[yaira2]

@Josh65-2201 Try to clean and rebuild the solution.

[Josh65-2201]

It works after cleaning and as expected.

[yaira2]

LGTM