added linux feature flag to enable 5ghz hotspot

internal/platform/implementation/linux/linux_flags.h

@@ -0,0 +1,25 @@
+// Copyright 2026 Google LLC
+//
+// Licensed 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
+//
+//     https://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.
+
+#ifndef PLATFORM_IMPL_LINUX_LINUX_FLAGS_H_
+#define PLATFORM_IMPL_LINUX_LINUX_FLAGS_H_
+
+namespace nearby::linux {
+
+bool Is5GhzHotspotEnabled();
+void Set5GhzHotspotEnabled(bool enabled);
+
+}  // namespace nearby::linux
+
+#endif  // PLATFORM_IMPL_LINUX_LINUX_FLAGS_H_