When focus is on a dock panel that doesn't contain a pane (e.g., project
panel), `pane::CloseActiveItem` will now close the active item in the center
pane instead of doing nothing.

This allows users to bind, for example, `cmd-w` to `pane::CloseActiveItem` 
and have it work consistently regardless of whether focus is on a dock 
panel or the editor.

Closes #45261

Release Notes:

- Improved `pane::CloseActiveItem` to close center pane items even when
focus is on a dock panel like the project panel or outline panel

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Co-authored-by: dino <dinojoaocosta@gmail.com>