Handle PowerShell keywords case-insensitively (#1482)

Author: Widthdom

src/CodeIndex/Indexer/References/ReferenceExtractor.cs

@@ -222,7 +222,7 @@ private static bool IsFunctionLikeSymbolKind(string kind)
             "import", "importFrom", "export", "exportClasses", "exportMethods", "S3method", "useDynLib",
         },
         // PowerShell keywords / PowerShell キーワード
-        ["powershell"] = new HashSet<string>(StringComparer.Ordinal)
+        ["powershell"] = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
         {
             "function", "filter", "configuration", "workflow", "class", "enum",
             "param", "begin", "process", "end", "dynamicparam",

tests/CodeIndex.Tests/ReferenceExtractorTests.cs

@@ -18308,6 +18308,7 @@ function MyFunction {
             filter Select-Valid {
                 process { if ($_.IsValid) { return $_ } }
             }
+            IF ($true) { RETURN "ok" }
 
             function Process-Items {
                 param([array]$Items)
@@ -18341,7 +18342,7 @@ function Process-Items {
         Assert.Contains(references, r => r.SymbolName == "Invoke-RestMethod" && r.ReferenceKind == "call");
         Assert.Contains(references, r => r.SymbolName == "ForEach-Object" && r.ReferenceKind == "call");
         Assert.Contains(references, r => r.SymbolName == "Where-Object" && r.ReferenceKind == "call");
-        Assert.DoesNotContain(references, r => r.SymbolName is "function" or "filter" or "if" or "return");
+        Assert.DoesNotContain(references, r => r.SymbolName is "function" or "filter" or "if" or "IF" or "return" or "RETURN");
         Assert.DoesNotContain(references, r => r.SymbolName == "lt");
     }