Add a placeholder example for generating tests app (project-chip#10193)

Add examples/placeholder with some default zap file that can be compiled with ./scripts/examples/gn_build_test_example.sh app1

Author: vivien-apple

examples/placeholder/linux/.gn

@@ -0,0 +1,25 @@
+# Copyright (c) 2021 Project CHIP Authors
+#
+# 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.
+
+import("//build_overrides/build.gni")
+
+# The location of the build configuration file.
+buildconfig = "${build_root}/config/BUILDCONFIG.gn"
+
+# CHIP uses angle bracket includes.
+check_system_includes = true
+
+default_args = {
+  import("//args.gni")
+}

examples/placeholder/linux/BUILD.gn

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+# Copyright (c) 2021 Project CHIP Authors
+#
+# 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.
+
+import("//build_overrides/build.gni")
+import("//build_overrides/chip.gni")
+
+import("${chip_root}/src/app/chip_data_model.gni")
+
+declare_args() {
+  chip_tests_zap_config = "none"
+}
+
+chip_data_model("configuration") {
+  zap_file = "apps/${chip_tests_zap_config}/zap.config"
+
+  zap_pregenerated_dir = "${chip_root}/out/debug/placeholder/${chip_tests_zap_config}/zap-generated"
+  is_server = true
+}
+
+executable("chip-${chip_tests_zap_config}") {
+  sources = [ "main.cpp" ]
+
+  deps = [
+    ":configuration",
+    "${chip_root}/examples/platform/linux:app-main",
+    "${chip_root}/src/lib",
+  ]
+
+  cflags = [ "-Wconversion" ]
+
+  output_dir = root_out_dir
+}
+
+group("linux") {
+  deps = [ ":chip-${chip_tests_zap_config}" ]
+}

examples/placeholder/linux/apps/app1/include/CHIPProjectConfig.h

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+/*
+ *
+ *    Copyright (c) 2020-2021 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.
+ */
+
+/**
+ *    @file
+ *          Example project configuration file for CHIP.
+ *
+ *          This is a place to put application or project-specific overrides
+ *          to the default configuration values for general CHIP features.
+ *
+ */
+
+#pragma once
+
+// Use a default pairing code if one hasn't been provisioned in flash.
+#define CHIP_DEVICE_CONFIG_USE_TEST_SETUP_PIN_CODE 20202021
+#define CHIP_DEVICE_CONFIG_USE_TEST_SETUP_DISCRIMINATOR 0xF02