feat(cmakev2/project): add idf_project_default macro

The idf_project_default macro is intended to be used by default for
ESP-IDF projects. Currently, it handles the necessary project
initialization that must occur after CMake's project() is called. It
creates the default executable based on the project name and links a
library to it, based on the main component and its transitive
dependencies. This macro will be further extended to also generate
binary image, project metadata, and add other expected targets. It
primarily serves as a replacement for the project() macro used in
cmakev1.

Expected typical usage:
```
cmake_minimum_required(VERSION 3.22)
include($ENV{IDF_PATH}/tools/cmakev2/idf.cmake)
project(hello_world LANGUAGES C CXX ASM)
idf_project_default()
```

Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>

tools/cmakev2/project.cmake

@@ -592,3 +592,22 @@ function(__generate_project_info)
     configure_file("${IDF_PATH}/tools/cmake/project_description.json.in"
         "${BUILD_DIR}/project_description.json")
 endfunction()
+
+#[[api
+.. cmakev2:macro:: idf_project_default
+
+   .. code-block:: cmake
+
+      idf_project_default()
+
+   Create a default project executable based on the main component and its
+   transitive dependencies. The executable name is derived from the
+   PROJECT_NAME variable, which by default uses the CMAKE_PROJECT_NAME value
+   specified in the CMake's project() call.
+#]]
+macro(idf_project_default)
+    idf_project_init()
+    idf_build_get_property(project_name PROJECT_NAME)
+    idf_build_executable("${project_name}" COMPONENTS main SUFFIX ".elf")
+    unset(project_name)
+endmacro()

tools/cmakev2/test/CMakeLists.txt

@@ -222,6 +222,9 @@ test_project_properties()
 test_include_component()
 test_executable()
 
+# Create default project
+idf_project_default()
+
 # Call this test last because it replaces the ESP system component.
 test_component_priority()
 

tools/cmakev2/test/components/main/CMakeLists.txt

@@ -0,0 +1,3 @@
+idf_component_register(SRCS "hello_world_main.c"
+                       PRIV_REQUIRES spi_flash
+                       INCLUDE_DIRS "")

tools/cmakev2/test/components/main/hello_world_main.c

@@ -0,0 +1,51 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <stdio.h>
+#include <inttypes.h>
+#include "sdkconfig.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_chip_info.h"
+#include "esp_flash.h"
+#include "esp_system.h"
+
+void app_main(void)
+{
+    printf("Hello world!\n");
+
+    /* Print chip information */
+    esp_chip_info_t chip_info;
+    uint32_t flash_size;
+    esp_chip_info(&chip_info);
+    printf("This is %s chip with %d CPU core(s), %s%s%s%s, ",
+           CONFIG_IDF_TARGET,
+           chip_info.cores,
+           (chip_info.features & CHIP_FEATURE_WIFI_BGN) ? "WiFi/" : "",
+           (chip_info.features & CHIP_FEATURE_BT) ? "BT" : "",
+           (chip_info.features & CHIP_FEATURE_BLE) ? "BLE" : "",
+           (chip_info.features & CHIP_FEATURE_IEEE802154) ? ", 802.15.4 (Zigbee/Thread)" : "");
+
+    unsigned major_rev = chip_info.revision / 100;
+    unsigned minor_rev = chip_info.revision % 100;
+    printf("silicon revision v%d.%d, ", major_rev, minor_rev);
+    if (esp_flash_get_size(NULL, &flash_size) != ESP_OK) {
+        printf("Get flash size failed");
+        return;
+    }
+
+    printf("%" PRIu32 "MB %s flash\n", flash_size / (uint32_t)(1024 * 1024),
+           (chip_info.features & CHIP_FEATURE_EMB_FLASH) ? "embedded" : "external");
+
+    printf("Minimum free heap size: %" PRIu32 " bytes\n", esp_get_minimum_free_heap_size());
+
+    for (int i = 10; i >= 0; i--) {
+        printf("Restarting in %d seconds...\n", i);
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+    }
+    printf("Restarting now.\n");
+    fflush(stdout);
+    esp_restart();
+}