Strip UTF-8 BOM from ApiCheck source files

CI's EditorConfig check failed with "Wrong character encoding (UTF-8-SIG
instead of utf-8)" on seven files that were committed with a byte-order mark.
The repo's .editorconfig requires charset = utf-8 (no BOM). Remove the BOM
from each; no other content changes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: paulirwin

src/Lucene.Net/Support/Reflection/LuceneBaseTypeDifferenceAttribute.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 
 namespace Lucene.Net.Reflection
 {

src/Lucene.Net/Support/Reflection/LuceneInterfaceDifferenceAttribute.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 
 namespace Lucene.Net.Reflection
 {

src/Lucene.Net/Support/Reflection/LuceneModifierDifferenceAttribute.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 
 namespace Lucene.Net.Reflection
 {

src/dotnet/Lucene.Net.ApiCheck/Extensions/FieldInfoExtensions.cs

@@ -1,4 +1,4 @@
-/*
+/*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.

src/dotnet/Lucene.Net.ApiCheck/Extensions/StringExtensions.cs

@@ -1,4 +1,4 @@
-/*
+/*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.

src/dotnet/Lucene.Net.ApiCheck/Models/Diff/MemberReference.cs

@@ -1,4 +1,4 @@
-/*
+/*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.

src/dotnet/Lucene.Net.ApiCheck/Models/Diff/ModifierSet.cs

@@ -1,4 +1,4 @@
-/*
+/*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.