IGNITE-26858 Add CODEOWNERS for platforms (#12613)

https://issues.apache.org/jira/browse/IGNITE-26858

Author: ptupitsyn

CODEOWNERS

@@ -0,0 +1,21 @@
+# 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.
+
+# This file specifies the code owners for the different parts of the repository.
+# See also: https://cwiki.apache.org/confluence/display/IGNITE/How+to+Contribute#HowtoContribute-AppendixA.Componentsandtheirmaintainers
+
+# Platforms
+/modules/platforms/dotnet/    [email protected]
+/modules/platforms/cpp/       [email protected]