[Backport][2021.2][ShaderGraph] Bump Searcher package dependency to 4.9.1

com.unity.shadergraph/CHANGELOG.md

@@ -55,6 +55,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
   - Added many node synonyms for the Create Node search so that it's easier to find nodes.
 
 ### Changed
+ - Updated searcher package dependency version to 4.9.1
 - Properties and Keywords are no longer separated by type on the blackboard. Categories allow for any combination of properties and keywords to be grouped together as the user defines.
 - Vector2/Vector3/Vector4 property types will now be properly represented by a matching Vector2/Vector3/Vector4 UI control in the URP + HDRP Material Inspector as opposed to the fallback Vector4 field that was used for any multi-dimensional vector type in the past.
 - Updated/corrected View Direction documentation
@@ -71,6 +72,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Changed "Create Node" action in ShaderGraph stack separator context menu to "Add Block Node" and added it to main stack context menu
 
 ### Fixed
+ - Fixed a usability issue where in some cases searcher would suggest one collapsed category of results that user would have to manually expand anyway
+ - Fixed bug that causes search results to not be visible sometimes in the searcher window [1366061]
+ - Fixed bug that causes exceptions to be thrown when using the up/down arrow keys with search list focused [1358016]
+ - Fixed bug that causes some searcher items to be irreversibly collapsed due to expand icon disappearing on collapsing those items [1366074]
+ - Fixed bug that caused incorrect search results with non whitespaced queries for nodes with spaces in their name and for subgraphs [1359158]
 - Fixed bug where it was not possible to switch to Graph Settings tab in Inspector if multiple nodes and an edge was selected [1357648] (https://fogbugz.unity3d.com/f/cases/1357648/)
 - Fixed an issue where fog node density was incorrectly calculated.
 - Fixed inspector property header styling

com.unity.shadergraph/Editor/Drawing/SearchWindowAdapter.cs

@@ -90,7 +90,7 @@ private int ComputeScoreForMatch(string[] queryTerms, SearcherItem matchItem)
         public override SearcherItem OnSearchResultsFilter(IEnumerable<SearcherItem> searchResults, string searchQuery)
         {
             if (searchQuery.Length == 0)
-                return searchResults.FirstOrDefault();
+                return GetFirstChildItem(searchResults.FirstOrDefault());
 
             // Sort results by length so that shorter length results are prioritized
             // prevents entries with short names getting stuck at end of list after entries with longer names when both contain the same word

com.unity.shadergraph/package.json

@@ -6,7 +6,7 @@
   "displayName": "Shader Graph",
   "dependencies": {
     "com.unity.render-pipelines.core": "12.1.1",
-    "com.unity.searcher": "4.8.0"
+    "com.unity.searcher": "4.9.1"
   },
   "samples": [
     {