[two_dimensional_scrollables] prepare for const AnimationStyle (flutter#8397)

unblocks flutter/flutter#160564

Will go back through and implement `const` constructors in these spots once the framework PR lands.

Author: nate-thegrate

packages/two_dimensional_scrollables/lib/src/tree_view/tree.dart

@@ -496,6 +496,7 @@ class TreeView<T> extends StatefulWidget {
 
   /// The default [AnimationStyle] used for node expand and collapse animations,
   /// when one has not been provided in [toggleAnimationStyle].
+  // ignore: prefer_const_constructors
   static AnimationStyle defaultToggleAnimationStyle = AnimationStyle(
     curve: defaultAnimationCurve,
     duration: defaultAnimationDuration,

packages/two_dimensional_scrollables/test/tree_view/render_tree_test.dart

@@ -505,6 +505,7 @@ void main() {
         // Customize the animation
         treeView = TreeView<String>(
           tree: treeNodes,
+          // ignore: prefer_const_constructors
           toggleAnimationStyle: AnimationStyle(
             duration: const Duration(milliseconds: 500),
             curve: Curves.bounceIn,

packages/two_dimensional_scrollables/test/tree_view/tree_test.dart

@@ -546,6 +546,7 @@ void main() {
       // Default
       expect(
         style,
+        // ignore: prefer_const_constructors
         AnimationStyle(
           duration: TreeView.defaultAnimationDuration,
           curve: TreeView.defaultAnimationCurve,
@@ -574,6 +575,7 @@ void main() {
       await tester.pumpWidget(MaterialApp(
         home: TreeView<String>(
           tree: simpleNodeSet,
+          // ignore: prefer_const_constructors
           toggleAnimationStyle: AnimationStyle(
             curve: Curves.easeIn,
             duration: const Duration(milliseconds: 200),
@@ -757,6 +759,7 @@ void main() {
         home: TreeView<String>(
           tree: tree,
           controller: controller,
+          // ignore: prefer_const_constructors
           toggleAnimationStyle: AnimationStyle(
             curve: Curves.easeInOut,
             duration: Duration.zero,
@@ -843,6 +846,7 @@ void main() {
         home: TreeView<String>(
           tree: tree,
           controller: controller,
+          // ignore: prefer_const_constructors
           toggleAnimationStyle: AnimationStyle(
             curve: Curves.easeInOut,
             duration: const Duration(milliseconds: 200),