FIX: ISXB-1316 persist editor splitter positions when saving (#2131)

Author: smnwttbr

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -14,6 +14,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed an issue where removing a newly created action in the Asset Editor would cause an exception. [UUM-95693](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-95693)
 - Fixed arrow key navigation of Input Actions after Action rename. [ISXB-1024](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1024)
 - Fixed gamepad navigation in UI Toolkit TextField when using InputSystemUIInputModule. [UUM-77364](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-77364)
+- Fixed issue where asset editor window splitter positions were not persisted [ISXB-1316]
 
 ## [1.13.0] - 2025-02-05
 

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/PackageResources/InputActionsEditor.uxml

@@ -17,7 +17,7 @@
             </uie:Toolbar>
         </ui:VisualElement>
         <ui:VisualElement name="body" style="flex-direction: column; flex-grow: 1;">
-            <ui:TwoPaneSplitView name="actions-split-view" fixed-pane-initial-dimension="200">
+            <ui:TwoPaneSplitView name="actions-split-view" fixed-pane-initial-dimension="200" view-data-key="actions-editor-splitter-1">
                 <ui:VisualElement name="action-maps-container" class="body-panel-container actions-container">
                     <ui:VisualElement name="header" class="body-panel-header">
                         <ui:Label text="Action Maps" display-tooltip-when-elided="true" style="flex-grow: 1;" />
@@ -28,7 +28,7 @@
                     </ui:VisualElement>
                     <ui:VisualElement name="rclick-area-to-add-new-action-map" style="flex-direction: column; flex-grow: 1;" />
                 </ui:VisualElement>
-                <ui:TwoPaneSplitView name="actions-and-properties-split-view" fixed-pane-index="1" fixed-pane-initial-dimension="320" style="height: auto; min-width: 450px;">
+                <ui:TwoPaneSplitView name="actions-and-properties-split-view" fixed-pane-index="1" fixed-pane-initial-dimension="320" style="height: auto; min-width: 450px;" view-data-key="actions-editor-splitter-2">
                     <ui:VisualElement name="actions-container" class="body-panel-container">
                         <ui:VisualElement name="header" class="body-panel-header" style="justify-content: space-between;">
                             <ui:Label text="Actions" display-tooltip-when-elided="true" name="actions-label" />