Implement User Directed Commissioning - Phase 2 (#8084)

* second round of UDC feature

* build fixes

* build fixes

* CI build fixes

* CI build fixes

* CI build fixes - Android

* CI build fixes

* CI linux build fix

* Restyled by whitespace (#8247)

Co-authored-by: Restyled.io <commits@restyled.io>

* address comments

* address comments

* address comments

* address comments

* address comments

* revert changes to echo requester/responder

* fix CI builds

Co-authored-by: restyled-io[bot] <32688539+restyled-io[bot]@users.noreply.github.com>
Co-authored-by: Restyled.io <commits@restyled.io>
diff --git a/examples/platform/linux/ControllerShellCommands.h b/examples/platform/linux/ControllerShellCommands.h
new file mode 100644
index 0000000..82b65aa
--- /dev/null
+++ b/examples/platform/linux/ControllerShellCommands.h
@@ -0,0 +1,31 @@
+/*
+ *
+ *    Copyright (c) 2021 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    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
+ *
+ *        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.
+ */
+
+/**
+ * @brief Registers shell commands for performing discovery (eg. of commissionable nodes) related to commissioning.
+ */
+
+#include <controller/CHIPDeviceController.h>
+
+namespace chip {
+namespace Shell {
+
+void RegisterDiscoverCommands(chip::Controller::DeviceCommissioner * commissioner);
+
+} // namespace Shell
+} // namespace chip