Filter out all but FlatLaf LAFs in IDE options UI.

Selection of other LAFs via --laf option or config file still works.

nb/ide.branding/core.windows/src/org/netbeans/core/windows/options/Bundle_nb.properties

@@ -0,0 +1,28 @@
+# 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.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+
+# Space separated list of LAF classes to hide in UI
+Laf_Excludes=MetalLookAndFeel \
+NimbusLookAndFeel \
+MotifLookAndFeel \
+WindowsLookAndFeel \
+WindowsClassicLookAndFeel \
+AquaLookAndFeel \
+GTKLookAndFeel \
+DarkMetalLookAndFeel \
+DarkNimbusLookAndFeel