Add multiple node deletion and undo auto-arrange

[RailKill]

This PR does the following:

• Allows deletion of multiple selected nodes using the Delete key. This action is undo-able.
• Allows undo-ing and redo-ing of the auto arrange node button introduced in Godot 4.3 graph edit.

Summary by Sourcery

Introduce the ability to delete multiple selected nodes with undo support and enhance the auto-arrange feature with undo/redo capabilities. Improve node selection and position management in the graph editor.

New Features:

• Enable deletion of multiple selected nodes using the 'Delete' key, with support for undoing this action.
• Add undo and redo functionality for the auto-arrange nodes feature in the graph editor.

Enhancements:

• Improve node selection handling by maintaining a list of selected nodes and updating node positions accordingly.
• Refactor the graph node selection and deselection logic to better manage active nodes and their positions.

[sourcery-ai[bot]]

Reviewer's Guide by Sourcery

This pull request implements two main features: multi-node deletion and undo/redo functionality for the auto-arrange feature in the graph editor. The changes primarily affect the MonologueGraphEdit script, with minor adjustments to MonologueControl and SidePanelNodeDetails scripts. The implementation focuses on enhancing user interaction with the graph, improving selection handling, and integrating with the existing undo/redo system.

File-Level Changes

Files	Changes
Scripts/MonologueGraphEdit.gd	Implemented multi-node deletion functionality using the Delete key, integrated with the undo/redo system
Scripts/MonologueGraphEdit.gd	Added undo/redo support for the auto-arrange feature, recording node positions before and after arrangement
Scripts/MonologueGraphEdit.gd Scripts/SidePanelNodes/SidePanelNodeDetails.gd	Refactored node selection handling to support multiple selected nodes
Scripts/MonologueGraphEdit.gd Scripts/MonologueControl.gd Scripts/SidePanelNodes/SidePanelNodeDetails.gd	Improved management of active and selected nodes, including updates to the side panel behavior
Scripts/MonologueGraphEdit.gd	Removed redundant variables and simplified input handling in the graph edit script
Scripts/MonologueGraphEdit.gd Scripts/MonologueControl.gd	Updated node position tracking for undo/redo operations

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[atomic-junky]

It seems to work perfectly!