CI: add nightly scheduled execution, perform selective test execution upon targeted platform changes

As the micro_ros_setup keeps growing and adding new features, so it does its continuous integration system.

This leds to CI executions taking too much time and often slowing the development process.
Therefore, two enhancements are proposed:

• Perform a nightly CI execution, every 24 hours, where all the tests will be run.
• Based upon the platform (host, freertos...) in which the changes are taking place, run only those tests affected by these changes. This can be easily achieved thanks to this repo's folder structure.

该 issue 提议每晚执行完整测试，并针对指定平台执行选择性测试，但没有指明 workflow 文件、测试或 CI 入口点。首先定位 repository 的 CI 配置和特定平台的测试布局；完成标准是，计划的完整运行和针对变更的运行都执行预期的测试。