Add copy/cut/paste/duplicate functionality for path geometry (#2812)

* Copy and Paste for paths

* Fix merge

* Implement Copy, Cut and Duplicate

* Fix selection of segments

* Fix formatting

* Code review

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

editor/src/messages/tool/common_functionality/shape_editor.rs

@@ -57,6 +57,10 @@ pub struct SelectedLayerState {
 }
 
 impl SelectedLayerState {
+	pub fn is_empty(&self) -> bool {
+		self.selected_points.is_empty() && self.selected_segments.is_empty()
+	}
+
 	pub fn selected_points(&self) -> impl Iterator<Item = ManipulatorPointId> + '_ {
 		self.selected_points.iter().copied()
 	}