Add a 'Preserve Aspect Ratio' checkbox to Properties panel (#923)

* Add the link button

* Transform around pivot

* Remove log

* Fix tests

* Add a hacky two-line layout for the checkbox

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

document-legacy/src/operation.rs

@@ -245,6 +245,10 @@ pub enum Operation {
 		path: Vec<LayerId>,
 		name: String,
 	},
+	SetLayerPreserveAspect {
+		layer_path: Vec<LayerId>,
+		preserve_aspect: bool,
+	},
 	SetLayerBlendMode {
 		path: Vec<LayerId>,
 		blend_mode: BlendMode,