Restore handle length when Shift is released while dragging opposite handle with Path tool (#1009)

* Restore path handle length to previous length when shift is released while dragging

* Reset previous opposing handle length on Delete and Abort messages

* Move the opposing handle length state to the path tool

* Use MoveManipulatorPoint messages instead of modifying MoveSelectedManipulatorPoints + break handle mirroring on dragging both handles without anchor

* Handle alt + improve reset logic + comments

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Co-authored-by: Keavon Chambers <keavon@keavon.com>

node-graph/gcore/src/vector/manipulator_group.rs

@@ -146,6 +146,7 @@ impl ManipulatorGroup {
 
 		// If the anchor isn't selected, but both handles are, drag only handles
 		if self.both_handles_selected() {
+			self.editor_state.mirror_angle_between_handles = false;
 			for point in self.selected_handles_mut() {
 				move_point(point, delta);
 			}